Liquid adhesion promoter for cord-reinforced rubber and metal or polymer substrate/rubber composites

ABSTRACT

A rubber composition including a natural or synthetic rubber, and an adhesive resin capable of unexpected adhesion to metal, polymer and glass substrates, particularly cords in radical tires, hoses, conveyor belts, transmission belts, and the like by the addition of a liquid composition containing long chain esters, including mono, di- and trimesters.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation-in-part of U.S. patent application Ser.No. 10/301,770, filed Nov. 21, 2002, which is a continuation-in-part ofU.S. patent application Ser. No. 10/144,229, filed May 10, 2002, theentire respective disclosures of which are hereby incorporated byreference.

FIELD OF THE INVENTION

[0002] The present invention is directed to adhesion promoters foradhering elastomers, including natural and/or synthetic rubbers, tonatural or synthetic polymeric cord or fabric substrates, and/or metalcord or metal substrates, particularly cords in the manufacture ofcord-reinforced rubber articles, such as tires, hoses, conveyor belts,transmission belts, and the like.

BACKGROUND OF THE INVENTION

[0003] Many rubber articles, principally automobile tires, but alsoincluding hoses, conveyor belts, power train belts, e.g., transmissionbelts, and the like, are usually reinforced with fibrous or metal cords.In all such instances, the fiber must be firmly bonded to the rubber.This is so whether the fiber is a natural or synthetic polymer, ormetallic, and whether the rubbers are natural or synthetic.

[0004] The conventional practice has been to prepare the fiber bypretreatment with a combination of hexamethoxymelamine orhexamethylene-tetramine and phenol-formaldehyde condensation product,wherein the phenol is almost always resorcinol. By a mechanism notcompletely understood, the resin reacts with the fiber and the rubber,effecting a firm reinforcing bond.

[0005] One method for preparing rubber compositions reinforced withcords entails compounding a vulcanizing rubber stock composition withthe components of an adhesive resin condensation product. The componentsof the condensation product include a methylene acceptor and a methylenedonor. The most commonly employed methylene acceptor is a phenol, suchas resorcinol, while the most commonly employed methylene donor is amelamine, such as N-(substituted oxymethyl)melamine. The effect achievedis resin formation in-situ during vulcanization of the rubber, creatinga bond between the metal or polymeric cords and the rubber, irrespectiveof whether the cords have been pretreated with an additional adhesive,such as a styrene-butadiene latex, polyepoxides with a blockedisocyanate, and the like.

[0006] Resorcinol-free vulcanizable rubber compositions are known. Forexample, U.S. Pat. No. 5,298,539 discloses vulcanizable rubbercompositions containing uncured rubber, a vulcanizing agent and at leastone additive selected from the group consisting of derivatives ofmelamine, acetoguanamine, benzoguanamine, cyclohexylguanamine andglycoluril monomer and oligomers of these monomers. These derivativesare substituted on average at two or more positions on the monomer oreach unit of the oligomer with vinyl terminated radicals and thecomposition is free of resorcinol.

[0007] Another manner of eliminating resorcinol from vulcanizable rubbercompositions has relied on the use of alternative coreactants. U.S. Pat.No. 4,038,220 describes a vulcanizable rubber composition whichcomprises a rubber, a filler material, N-(substituted oxymethyl)melamineand at least one of α- or β-naphthol. This reference employs themonohydric phenols, α- or β-naphthol, as methylene acceptors in theresin forming reaction during vulcanization in the absence ofresorcinol. The use of resorcinol-formaldehyde resin to replaceresorcinol in vulcanizable rubber compositions is also known. Forexample, see A. Peterson, et al., “Resorcinol Bonding Systems for SteelCord Adhesion”, Rubber World (August 1984).

[0008] An increased need in the industry for fiber reinforcing of rubberto survive high dynamic stress, such as flexing, to avoid tire beltseparation has brought about a continuing search for other and bettermethods for achieving high adhesive strength.

[0009] Tires typically have a construction such that a carcass, edgeportions of a belt, an under-belt pad and the like are intricatelycombined with each other in its shoulder portion. The under-belt padprovided continuously along the circumferential shoulder portion of thetire between a tread rubber portion and the carcass and extendingoutwardly of the belt edge portions along the width of the tire is athick rubber layer, which is a structural characteristic for alleviatinga shear stress possibly generated between the belt edge portions and thecarcass. Further, since the under-belt pad is repeatedly subjected toloads during running, heat is liable to build-up in the under-belt pad,thereby causing internal rubber destruction in the under-belt pad andadhesion failures between the rubber components and between a rubberportion and cords (steel cords) in the carcass. This causes separationof the belt edge portions and ply separation in the carcass resulting inbreakdown of the tire. One conventional approach to this problem is thatthe under-belt pad is formed of a rubber compound which contains areduced amount of carbon black for suppression of heat build-up.

[0010] However, the rubber compound for the under-belt pad is softenedby the reduction of the carbon black content therein. This also resultsin the adhesion failure and the internal rubber destruction in theunder-belt pad due to the heat build-up, thereby causing the plyseparation and the belt separation in the tire during running.Therefore, this approach is not satisfactory in terms of the durabilityof the tire. The deterioration of the durability of the tire whichresults from the heat build-up attributable to the structuralcharacteristic of the under-belt pad is a more critical problem, sincethe recent performance improvement of automobiles requires that tireshave a higher durability under higher speed running and heavy loads.

[0011] Despite their good abrasion resistance, radial tires becomeunusable sooner than bias tires because of the belt separation whichtakes place while the tread still remains. One way that this problem hasbeen addressed is by improving the tread or steel cord-embedding rubber.For example, an improved tread is of dual layer structure, with theinner layer (base tread adjacent to the belt) being made of a rubbercomposition which is saved from heat generation at the sacrifice ofabrasion resistance, and the outer layer (cap tread) being made of arubber composition of high abrasion resistance. Also, an improved steelcord-embedding rubber is made of a rubber composition containing anadhesive such as a cobalt salt of an organic acid, hydroxybenzoic acid,and resorcinol, which increases adhesion between rubber and steel cord.These improvements, however, are not completely successful.

[0012] Other adhesion promoters have been used in an attempt to avoidbelt separation, for example, special latices such as, for example, avinyl-pyridine latex (VP latex) which is a copolymer of about 70%butadiene, about 15% styrene and about 15% 2-vinylpyridine. Examples ofother latices which are present in adhesion promoters are acrylonitrilerubber latices or styrene-butadiene rubber latices. These can be used assuch or in combination with one another. Especially suitable adhesionpromoters for polyesters are also those which are applied in multi-stageprocesses, for instance a blocked isocyanate being applied incombination with polyepoxide and the material then being treated usingcustomary resorcinol-formaldehyde resins (RFL dip). It is also known touse combinations of RFL dips with other adhesion-promoting substancessuch as, for example, a reaction product of triallyl cyanurate,resorcinol and formaldehyde or p-chlorophenol, resorcinol andformaldehyde.

[0013] Not only is it necessary that adhesion between rubber and metal,e.g., steel or polymeric cord be high, but it is also necessary that adecrease in adhesion be as small as possible while tires are in use. Inactuality, tires containing a steel cord-embedding rubber with goodadhesion occasionally lose the initial adhesion to a great extent afteruse. The following are the possible reasons why adhesion between steelcord and rubber decreases while tires are in use:

[0014] (1) Tires are subject to many minute cuts when they run overgravel or sharp objects. The cuts reaching the inside of the treadpermit air and moisture to infiltrate into the tire, promoting the agingand fatigue of the embedding rubber and also rusting the steel cord. Allthis leads to a decrease in adhesion.

[0015] (2) The adhesion improver incorporated into the steelcord-embedding rubber diffuses and migrates into the tread rubber duringvulcanization or tire use. This leads to a decrease in adhesion.

[0016] (3) The softener and other additives incorporated into the treadmigrate into the steel cord-embedding rubber. This also leads to adecrease in adhesion.

[0017] Despite the various proposals made to improve the adherence ofcord to rubber in vulcanizable rubber compositions, there is acontinuing need for commercially available cost effective additives thatimprove the adhesion of rubber to fibrous or metal cords in vulcanizablerubber compositions.

[0018] The adhesion promoter systems of the present invention farsurpass any extant adhesion promoters known in the art for adhesion ofmetal and/or polymeric cord to vulcanizable rubber.

SUMMARY OF THE INVENTION

[0019] In brief, it has been found that the use of long chain estersformed by reacting mono, di-, and/or tri-carboxylic acids containingone, two, or three C₆-C₂₄ long chain radicals or fatty acid residues,and alcohols containing a C₃-C₂₄ alkyl group, in a natural or syntheticvulcanizable rubber, unexpectedly increases the adhesion between therubber and a metal or polymeric substrate, such as metal or polymericsurfaces, particularly cords used in reinforcing rubber in tires, hoses,conveyor belts, motor mounts, automotive drive train belts, includingtransmission belts, and the like, when added with an adhesive resin,such as a melamine-containing resin or a phenol-, e.g.,resorcinol-containing resin, e.g., a Novolak resin. Examples of suitablesubstrates include steel, brass-coated steel, brass, polyester, Aramid,textiles, copper, glass, and the like. Application of the adhesivepromoters of the invention is particularly contemplated with steel cord,brass-coated steel cord, brass cord, polyester fiber cord, Aramid fibercord, glass cord, fabric and flat metal surfaces, and the like. Whilethese resins have been used before to adhere metal tire cord to avulcanizable rubber, and theoretically bond the rubber to the resin,surprisingly good adhesion has been found by additionally adding one ormore long chain mono-, di-, and/or tri-esters, particularly dimerateesters reacted from C₁₈ fatty acids, and C₃-C₂₄ alcohols, preferably,C₃-C₁₈ alcohols, more preferably C₆-C₁₈ alcohols. Preferably, the estersprovide unexpected, tenacious bonding between polymeric or metal cordand rubber, when combined with an adhesive resin. It is theorized thatthe long chain esters of the invention strongly adhere both to therubber and to the resin, with the resin providing sufficient ionicbonding to the reinforcing cords.

[0020] One aspect of the composition and articles described herein is toprovide a radial tire for heavy load vehicles characterized by goodadhesion between steel or polymeric cord and steel cord-embeddingrubber, said adhesions lasting for a long time with only a small loss ofadhesion while tires are in use. Another aspect of the compositions andarticles described herein is to provide a radial tire for vehicles andother cord-embedded rubber articles which are superior in cord adhesionto rubber.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The adhesion promoter systems of the invention include at leastone long chain ester compound and at least one adhesive resin. Theadhesion promoter systems are useful for improving the adhesion ofrubber to metal and polymeric substrates, particularly metal andpolymeric cord. Surprisingly, the adhesion promoter systems disclosedherein significantly increase the adhesion of rubber compositions tosuch metal and polymeric substrates. In the description, the terms“adhesion promoter system” and “adhesion promoter” may be usedinterchangeably.

[0022] In the adhesion promoter systems of the invention, long chainesters are typically added to natural or synthetic rubber with avulcanizing agent and an adhesive resin. The adhesion promoter systemsmay be added to a natural and/or synthetic rubber(s), as a neat liquid,in order to promote adhesion. Typically, however, the adhesion promotersare mixed with a dry carrier, such as calcium silicate, to form analternative delivery system, which can be incorporated into naturaland/or synthetic rubber(s). In such a method, the carrier facilitatesdelivery of the active adhesion promoting agents to the rubber(s). Inyet another refinement of the invention, the adhesion promoter may beformulated as a “polymer masterbatch.” According to this aspect of theinvention, a pellet comprising polymer (about 6 wt. % to about 20 wt.%), filler or inert ingredients (about 0 wt. % to about 14 wt. %), withthe balance being an adhesion promoter system (i.e., at least one estercompound in accordance with formulas I-IV and at least one adhesiveresin such as melamine) is added to a natural or synthetic rubber.Typically, the masterbatch polymer and the rubber to which themasterbatch polymer is added are miscible. Preferably, the masterbatchpolymer and the rubber are the same.

[0023] Throughout the specification, the adhesion promoter systems aregenerally used in an amount between about 0.2% by weight and about 30%by weight. Typically, each component of an adhesion promoter system ofthe invention (i.e., an ester in accordance with formulas I-IV and anadhesive resin) is present in an amount between about 0.1% and about 15%by weight, usually between about 1 wt. % and about 10 wt. %, and mostpreferably between about 2 wt. % and about 8 wt. %, based on the weightof natural and synthetic rubber in the composition.

[0024] Ranges may be expressed herein as from “about” or “approximately”one particular value and/or to “about” or “approximately” anotherparticular value. When such a range is expressed, another embodimentincludes from the one particular value and/or to the other particularvalue. Similarly, when values are expressed as approximations, by use ofthe antecedent “about,” it will be understood that the particular valueforms another embodiment.

[0025] The long chain esters may be monoesters, diesters, triesters, ormixtures thereof, that may include saturated or unsaturated hydrocarbonchains, straight chain or branched having none, one, two or three doublebonds in the hydrocarbon chains.

[0026] The monoesters have a formula I, as follows:

[0027] wherein R¹ is a C₃-C₂₄ alkyl, preferably C₃-C₁₈ alkyl, morepreferably C₆-Cl8 alkyl, straight chain or branched, saturated orunsaturated containing 1 to 3 carbon-to-carbon double bonds. R² is aC₃-C₂₄, preferably C₆-C₂₄, more preferably C₈-C₁₈ saturated hydrocarbon,or an unsaturated hydrocarbon having 1 to 6, preferably 1 to 3carbon-to-carbon double bonds.

[0028] The diesters have a formula II or III, as follows:

[0029] wherein n=3-24, preferably 6-18, and more preferably 3-10, and R³and R⁴, same or different, are C₃-C₂₄ alkyl, preferably C₃-C₁₈ alkyl,more preferably C₆-C₁₈ alkyl radicals, straight chain or branched,saturated or unsaturated containing 1 to 3 carbon-to-carbon doublebonds.

[0030] wherein R⁵ and R⁷, same or different, are C₃-C₂₄ alkyl,preferably C₆-C₂₄ alkyl, more preferably C₈-C₁₈ alkyl, straight chain orbranched, either saturated or containing 1 to 6, preferably 1 to 3,carbon-to-carbon double bonds;

[0031] R⁶ and R⁸, same or different, are C₃-C₂₄ alkyl, preferably C₃-C₁₈alkyl, more preferably C₆-C₁₈ alkyl, straight chain or branched,saturated or unsaturated containing 1 to 3 carbon-to-carbon doublebonds; and

[0032] R¹⁰ and R¹¹, same or different, are C₃-C₂₄ saturated hydrocarbonchains, preferably C₃-C₁₈, more preferably C₆-C₁₈, straight chain orbranched; or unsaturated C₃-C₂₄ hydrocarbon chains, preferably C₃-C₁₈,more preferably C₆-C₁₈, straight chain or branched, containing 1 to 6,preferably 1 to 3, carbon-to-carbon double bonds.

[0033] The triesters have a formula IV, as follows:

[0034] wherein R¹², R¹⁴ and R¹⁸, same or different, are C₃-C₂₄ alkyl,preferably C₆-C₂₄ alkyl, more preferably C₈-C₁₈ alkyl, straight chain orbranched, either saturated or containing 1 to 6, preferably 1 to 3,carbon-to-carbon double bonds;

[0035] R¹³, R¹⁵ and R¹⁹, same or different, are C₃-C₂₄ alkyl, preferablyC₃-C₁₈ alkyl, more preferably C₆-C₁₈ alkyl, straight chain or branched,saturated or unsaturated containing 1 to 3 carbon-to-carbon doublebonds; and

[0036] R¹⁶, R¹⁷ and R²⁰, same or different, are C₃-C₂₄ saturatedhydrocarbon chains, preferably C₃-C₁₈, more preferably C₆-C₁₈, straightchain or branched; or unsaturated C₃-C₂₄ hydrocarbon chains, preferablyC₃-C₁₈, more preferably C₆-C₁₈ straight chain or branched, containing 1to 6, preferably 1 to 3, carbon-to-carbon double bonds.

[0037] The fatty acid residues or hydrocarbon chains R², R⁵, R⁷, R¹²,R¹⁴ and R¹⁸ of the esters of formulas I, II, III, and IV can be anyC₃-C₂₄, preferably C₆-C₂₄, more preferably C₈-C₁₈, hydrocarbon chain,either saturated or containing 1 to 6, preferably 1 to 3,carbon-to-carbon double bonds, derived from animal or vegetable fattyacids such as butter; lard; tallow; grease; herring; menhaden; pilchard;sardine; babassu; castor; coconut; corn; cottonseed; jojoba; linseed;oiticica; olive; palm; palm kernel; peanut; rapeseed; safflower; soya;sunflower; tall; and/or tung. Examples are the hydrocarbon chainresidues from the following fatty acids, where the number in parenthesesindicates the number of carbon atoms, and the number of double bonds,e.g., (C₂₄₋₆) indicates a hydrocarbon chain having 24 carbon atoms and 6double bonds: Hexanoic (C₆₋₀); Octanoic (C₈₋₀); Decanoic (C₁₀₋₀);Dodecanoic (C₁₂₋₀); 9-Dodecenoic (CIS) (C₁₂₋₁); Tetradecanoic (C₁₄₋₀);9-Tetradecenoic (CIS) (C₁₄₋₁); Hexadecanoic (CIS) (C₁₆₋₀);9-Hexadecenoic (CIS) (C₁₆₋₁); Octadecanoic (C₁₈₋₀); 9-Octadecenoic (CIS)(C₁₈₋₁); 9-Octadecenoic, 12-Hydroxy-(CIS) (C₁₈₋₂); 9, 12-Octadecadienoic(CIS, CIS) (C₁₈₋₂); 9, 12, 15 Octadecatrienoic (CIS, CIS, CIS) (C₁₈₋₃);9, 11, 13 Octadecatrienoic (CIS, TRANS, TRANS) (C₁₈₋₃); 9, 11, 13Octadecatrienoic, 4-Oxo (CIS, TRANS, TRANS) (C₁₈₋₃); Octadecatetrenoic(C₁₈₋₄); Eicosanoic (C₂₀); 11-Eicosenoic (CIS) (C₂₀₋₁); Eicosadienoic(C₂₀₋₂); Eicosatrienoic (C₂₀₋₃); 5, 8, 11, 14 Eicosatetraenoic (C₂₀₋₄);Eicosapentaenoic (C₂₀₋₅); Docosanoic (C₂₂); 13 Docosenoic (CIS) (C₂₂₋₁);Docosatetraenoic (C₂₂₋₄); 4, 8, 12, 15, 19 Docosapentaenoic (C₂₂₋₅);Docosahexaenoic (C₂₂₋₆); Tetracosenoic (C₂₄₋₁); and 4, 8, 12, 15, 18, 21Tetracosahexaenoic (C₂₄₋₆).

[0038] Examples of particularly useful diesters of formula II include asaturated diester formed by the reaction of sebacic acid and2-ethylhexyl alcohol:

[0039] Other useful diesters falling within formula II include thesaturated diester formed by the reaction of sebacic acid with tridecylalcohol,

[0040] and the unsaturated diester formed by reaction of sebacic alcoholwith oleyl alcohol:

[0041] Useful cyclic diesters falling within formula III includedimerate ester structures formed by the reaction of a C₃₆ dimer acidderived from tall oil fatty acids and C₃-C₂₄, preferably C₃-C₁₈, morepreferably C₆-C₁₈ alcohol, straight chain or branched, saturated orunsaturated containing 1 to 3 carbon-to-carbon double bonds. Examples ofsuch cyclic esters include the following structures, wherein the dimeracid corresponding to structure A is formed by self reaction of linoleicacid, the dimer acid corresponding to structure B is formed by reactinglinoleic acid with oleic acid, and the dimer acid corresponding tostructure C is formed by reacting linoleic acid with linolenic acid:

[0042] wherein each R, same or different, in formulas (A), (B), and (C)is a C₃-C₂₄ radical, preferably C₃-C₁₈, more preferably C₆-C₁₈, straightchain or branched, saturated or unsaturated containing 1 to 3carbon-to-carbon double bonds. RX-13804 is another example of anunsaturated diester (dimerate ester) formed by the reaction of apredominantly C₃₆ dimer acid reacted with 2-ethylhexyl alcohol. RX-13824is an additional unsaturated diester (dimerate ester) formed by thereaction of a predominantly C₃₆ dimer acid with tridecyl alcohol.

[0043] A representative example of the triester (trimerate ester) offormula IV is the following structure (D);

[0044] wherein each R¹, R², and R³, same or different, is a C₃-C₂₄radical, preferably C₃-C₁₈, more preferably C₆-C₁₈, straight chain, orbranched, saturated or unsaturated containing 1 to 3 carbon-to-carbondouble bonds.

[0045] A particularly useful blend of long chain esters is formed fromblends of mono, dimer, and trimer acids, for example, products havingCAS#: 61788-89-4. Esters prepared from such products are blendsincluding, primarily, the above C₃₆ and C₅₄ dimerate and trimerateesters (A), (B), (C) and (D), shown in the above structures, that ispredominantly (more than 50% by weight) the C₃₆ dimerate esters (A), (B)and (C).

[0046] Commercially available blends of useful polybasic acids that canbe reacted with C₃-C₂₄, preferably C₃-C₁₈, more preferably C₆-C₁₈alcohols, straight chain or branched, saturated or unsaturatedcontaining 1 to 3 carbon-to-carbon double bonds to produce the dimerateand trimerate esters, as blends, include the following: EMPOL® 1010Dimer Acid; EMPOL® 1014 Dimer Acid; EMPOL® 1016 Dimer Acid; EMPOL® 1018Dimer Acid; EMPOL® 1022 Dimer Acid; EMPOL® 1024 Dimer Acid; EMPOL® 1040Trimer Acid; EMPOL® 1041 Trimer Acid; EMPOL® 1052 Polybasic Acid; andsimilar PRIPOL™ products from Uniqema as well as UNIDYME® products fromArizona Chemical.

[0047] Particularly useful long chain ester additives are made byreacting any of the long chain mono, dimer and/or trimer acids with oneor more straight chain or branched C₃-C₂₄, preferably C₃-C₁₈, morepreferably C₆-C₁₈ alcohols to produce the esters of formulas I, II, IIIand IV. The above dimer, trimer, and polybasic acids are produced bydimerizing, trimerizing, and polymerizing (oligomerizing) long chaincarboxylic acids from the above-mentioned fatty acids. The fatty acidsmay be mixtures. Accordingly, the dimer acid produced by dimerizing aC₁₈ carboxylic acid (typically, a mixture of stearic, oleic, linoleic,and linolenic), after esterification, will result in a blend of numerousdimerate and trimerate esters in accordance with formulas III and IV,including saturated and unsaturated esters (i.e., some long chain estersmay contain hydrocarbon chains having 1 to 6, generally 1 to 3,carbon-to-carbon double bonds). Any one, or any blend, of the esters offormulas I, II, III and/or IV, when combined with an adhesive resin,will function to increase the adhesion of natural or synthetic rubber tometal or polymeric cord, metal or polymeric substrates, such aspolymeric woven or non-woven fabrics, and metal flat stock materials.

[0048] The adhesion promoters include an adhesive resin, whichpreferably is a condensation product of a formaldehyde or methylenedonor and a formaldehyde or methylene acceptor, either pre-condensed, orcondensed in-situ while in contact with the rubber. The term “methylenedonor” is intended to mean a compound capable of reacting with amethylene acceptor (such as resorcinol or its equivalent containing areactive hydroxyl group) and generate the resin outside of the rubbercomposition, or in-situ. Preferably, the components of the condensationproduct include a methylene acceptor and a methylene donor. The mostcommonly employed methylene acceptor is a phenol, such as resorcinol,while the most commonly employed methylene donor is a melamine, such asN-(substituted oxymethyl)melamine. The effect achieved is resinformation in-situ during vulcanization of the rubber, creating a bondbetween the metal or polymeric cords and the rubber, irrespective ofwhether the cords have been pretreated with an additional adhesive, suchas a styrene-butadiene latex, polyepoxides with a blocked isocyanate,and the like. The long chain ester additive/resin combinations describedherein are particularly useful with steel cord, where adhesivepretreatment has been largely ineffective.

[0049] Examples of methylene donors which are suitable for use in therubber compositions disclosed herein include melamine,hexamethylenetetramine, hexaethoxymethylmelamine,hexamethoxymethylmelamine, lauryloxymethyl-pyridinium chloride,ethoxymethylpyridinium chloride, trioxan hexamethoxy-methylmelamine, thehydroxy groups of which may be esterified or partly esterified, andpolymers of formaldehyde, such as paraformaldehyde. In addition, themethylene donors may be N-substituted oxymethylmelamines, of the generalformula:

[0050] wherein X is an alkyl having from 1 to 8 carbon atoms R³, R⁴, R⁵,R⁶ and R⁷ are individually selected from the group consisting ofhydrogen, an alkyl having from 1 to 8 carbon atoms and the group —CH₂OX.Specific methylene donors include hexakis(methoxymethyl)melamine;N,N′,N″trimethyl/N,N′,N″-trimethylol-melamine; hexamethylolmelamine;N,N′,N″-dimethylolmelamine; N-methylol-melamine; NN′-dimethylolmelamine;N,N′,N″-tris (methoxymethyl)melamine; andN,N′,N″-tributyl-N,N′,N″-trimethylol-melamine. The N-methylolderivatives of melamine are prepared by known methods.

[0051] The amount of methylene donor and methylene acceptor,pre-condensed or condensed in-situ, that are present in the rubbercomposition may vary. Typically, the amount of pre-condensed methylenedonor and methylene acceptor is present will range from about 0.1% toabout 15.0%; or each can be added separately in an amount of about 0.1%to about 10.0%, based on the weight of natural and/or synthetic rubberin the composition. Preferably, the amount of each of a methylene donorand methylene acceptor added for in-situ condensation ranges from about2.0% to about 5.0%, based on the weight of natural and/or syntheticrubber in the composition. The weight ratio of methylene donor to themethylene acceptor may vary. Generally speaking, the weight ratio willrange from about 1:10 to about 10:1. Preferably, the weight ratio rangesfrom about 1:3 to 3:1.

[0052] Resorcinol-free vulcanizable rubber compositions also are usefulin the rubber compositions described herein. For example,resorcinol-free adhesive resins and adhesive compounds useful in theadhesion promoter systems (i.e., when combined with the long chainesters described herein) include those described in U.S. Pat. Nos.5,891,938 and 5,298,539, both hereby incorporated by reference. The '938patent discloses vulcanizable rubber compositions containing an uncuredrubber and a self-condensing alkylated triazine resin having high iminoand/or methylol functionality. U.S. Pat. No. 5,298,539 discloses rubberadditives which are substituted derivatives based on cyclic nitrogencompounds such as melamine, acetoguanamine, cyclohexylguanamine,benzoguanamine, and similar alkyl, aryl or aralkyl substitutedmelamines, glycoluril and oligomers of these compounds. In particular,the adhesive resins and adhesive compounds which are useful as theadhesive resins in the rubber compositions described herein include thefollowing: adhesive resins selected from the group consisting ofderivatives of melamine, acetoguanamine, benzoguanamine,cyclohexylguanamine and glycoluril monomers and oligomers of thesemonomers, which have been substituted on average at two or morepositions on the monomer or on each unit of the oligomer with vinylterminated radicals, the vulcanizable rubber composition being free ofresorcinol; and, these derivatives which have been further substitutedon average at one or more positions with a radical which comprisescarbamylmethyl or amidomethyl.

[0053] Further, the adhesive resin can be any of the compounds of thefollowing formulas:

[0054] and positional isomers thereof,

[0055] wherein, in each monomer and in each polymerized unit of theoligomers, Y is selected from methyl, phenyl and cyclohexyl, and, onaverage,

[0056] at least two R are —CH₂-R¹,

[0057] and any remaining R are H, and

[0058] at least 2 R¹ are radicals selected from:

[0059] CH₂═C(R²)—C(O)—O—,

[0060] CH₂═C(R²)—C(O)—Z,

[0061] CH₂═C(R²)—C(O)—NH—, and

[0062] CH₂═C(R²)—CH₂—O—,

[0063] wherein R² is hydrogen or C₁-C₁₈ alkyl, and Z is a radicalselected from:

[0064] —O—CH₂—CH₂—O—,

[0065] —O—CH₂—CH(CH₃)—O—,

[0066] —O—CH₂—CH₂—CH₂—O—, and

[0067] —O—CH(C₂H₅)—O—, and

[0068] any remaining R¹ radicals are selected from

[0069] —O-R³,

[0070] —NH—C(O)—OR⁴, and

[0071] —NH—C(O)-R⁴, and

[0072] wherein R₃ is hydrogen or R₄, and

[0073] R₄ is a C₁-C₁₈ alkyl, alicyclic, hydroxyalkyl, alkoxyalkyl oraromatic radical, and in the oligomers,

[0074] P is 2 to about 10, and

[0075] L is methylene or the radical

[0076] —CH₂—O—CH₂—.

[0077] These adhesive compounds are particularly useful, wherein onaverage at least one R¹ in each monomer or in each oligomerized unit is—NH—C(O)—OR⁴, particularly the compounds of the following formulas:

[0078] Particularly useful adhesive resins include the above formulaswherein on average, at least one R radical in each monomer or in eacholigomerized unit is

[0079] —CH₂—NH—C(O)—OR⁴,

[0080] wherein R⁴ is a C₁-C₁₈ alkyl, alicyclic, hydroxyalkyl,alkoxyalkyl or aromatic radical, and wherein, on average, at least two Rradicals are selected from

[0081] CH₂═C(CH₃)—C(O)O—C₃H₆—O—CH₂—

[0082]  and

[0083] CH₂═CH₂—C(O)O—C₂H₄—O—CH₂—

[0084] and at least one R radical is selected from

[0085] —CH₂—NH—C(O)—O—CH₃, and

[0086] —CH₂—NH—C(O)—O—C₃H₇.

[0087] These adhesive resins and compounds can include additionaladditives, particularly those selected from hydroxymethylated andalkoxymethylated (alkoxy having 1-5 carbon atoms) derivatives ofmelamine, acetoguanamine, benzoguanamine, cyclohexylguanamine andglycoluril and their oligomers.

[0088] Additional adhesive resins useful in the rubber compositionsdescribed herein include self-condensing alkylated triazine resinsselected from the group consisting of (i), (ii), and (iii):

[0089] (i) a self-condensing alkylated triazine resin having at leastone of imino or methylol functionality and represented by the formula(I)

[0090] (ii) an oligomer of (i), or

[0091] (iii) a mixture of (i) and (ii), wherein

[0092] Z is —N(R)(CH₂OR¹), aryl having 6 to 10 carbon atoms, alkylhaving 1 to 20 carbon atoms or an acetyl group,

[0093] each R is independently hydrogen or —CH₂OR¹, and

[0094] each R¹ is independently hydrogen or an alkyl group having 1 to12 carbon atoms,

[0095] provided that at least one R is hydrogen or —CH₂OH and at leastone R¹ is selected from the alkyl group; and

[0096] wherein the vulcanizable rubber composition is substantially freeof methylene acceptor coreactants.

[0097] These adhesive resins are particularly useful wherein at leastone R group is hydrogen and/or wherein at least one R¹ group is a loweralkyl group having 1 to 6 carbon atoms, particularly where the adhesiveresin is a derivative of melamine, benzoguanamine, cyclohexylguanamine,or acetoguanamine, or an oligomer thereof.

[0098] One particularly useful alkylated triazine adhesive resin of theabove formula is wherein Z is —N(R)(CH₂OR¹).

[0099] Another manner of eliminating resorcinol in an adhesive resin forrubber compositions, also useful herein, is N-(substitutedoxymethyl)melamine and at least one of α- or β-naphthol. This adhesiveresin employs the monohydric phenols, α- or β-naphthol, as methyleneacceptors in the resin forming reaction during vulcanization in theabsence of resorcinol.

[0100] Other adhesive resins useful in the rubber compositions describedherein include special latices such as, for example, a vinyl-pyridinelatex (VP latex) which is a copolymer of about 70% butadiene, about 15%styrene and about 15% 2-vinylpyridine; acrylonitrile rubber latices; andstyrene-butadiene rubber latices. These can be used as such or incombination with one another. Another suitable adhesive resin usefulherein, particularly for polyesters, are those which are applied inmulti-stage processes, for instance a blocked isocyanate being appliedin combination with polyepoxide and the material then being treatedusing customary resorcinol-formaldehyde resins (RFL dip). Additionaluseful adhesive resins include combinations of RFL dips with otheradhesion-promoting substances such as, for example, a reaction productof triallyl cyanurate, resorcinol and formaldehyde or p-chlorophenol,resorcinol and formaldehyde.

[0101] Other suitable adhesive resins for use in the rubber and adhesionpromoters described herein include polyurethane resins, epoxy resins,phenol aldehyde resins, polyhydric phenol aldehyde resins, phenolfurfural resins, xylene aldehyde resins, urea formaldehyde resins,melamine formaldehyde resins, alkyd resins, polyester resins, and thelike.

[0102] Typically, in the adhesion promoter systems, at least one estercompound in accordance with formulas I-IV is combined with an adhesiveresin in a weight ratio between about 10 parts ester to about 1 partadhesive resin (i.e., a ratio of about 10: 1, ester to resin,respectively) and about 1 part ester to about 10 parts resin (i.e., aratio of about 1:10, ester to resin, respectively). More preferably, theesters are combined with an adhesive resin in a weight ratio betweenabout 4 parts ester to about 1 part adhesive resin and about 1 partester to about 4 parts resin. Most preferably, the ratio of ester toadhesive resin is approximately one to one in the adhesion promotersystems of the invention.

[0103] The initial work with the long chain esters involved testing theesters in industrial rubber belts containing polyester cords forautomotive power train systems. An important part of the construction ofautomotive belts is the bonding of the rubber to polyester cord.Polyester cord is used to provide strength and longevity to the belts.The polymer of choice for automotive belts is ethylene/propylene/dienepolymer (EPDM). This polymer is excellent for the end use, but one ofits drawbacks is poor adhesion to many substrates, such as polyestercord. Rubber companies go to great lengths to insure the proper adhesionbetween the EPDM and the polyester cord. At present, they use a treatedcord that has a resorcinol-formaldehyde resin coating, and theresin-coated cords are then dipped in an adhesive. The resin-treated,adhesive coated cord is then bonded to the EPDM during the curingprocess. This is a time-consuming and expensive method to achieverubber-to-polyester cord adhesion. The adhesion promoter systems of theinvention advantageously improve adhesion of polyester cord to EPDM.

[0104] Other examples of substrates which are contemplated for use inthe inventive compositions and methods include metal and polymericlayers, films, sheets, fibers, yams and/or fabrics, including textiles,polyesters, and Aramid fibers. Metals for use in the invention includesteel, brass-coated steel, brass, and copper. Adhesion to glasssubstrates can also be improved. Application of the adhesion promotersof the invention is particularly contemplated with steel cord,brass-coated steel cord, brass cord, polyester fiber cord, Aramid fibercord, glass cord, fabric and flat metal surfaces, and the like. In thepresent application the term polymeric “cord” or “cords” is intended toinclude reinforcing elements used in rubber products including fibers,continuous filaments, staple, tow, yarns, fabric and the like,particularly cords for use in building the carcasses of tires such astruck tires.

[0105] The polymeric reinforcing element or cord comprises a pluralityof substantially continuous fibers or monofilaments, including glasscompositions, polyesters, polyamides and a number of other materials,useful in making the fibers for the reinforcing element or cords forpolymeric rubber compositions and products are well known in the art.One of the preferred glasses to use is a glass known as E glass anddescribed in “Mechanics of Pneumatic Tires,” Clark, National Bureau ofStandards Monograph 122, U.S. Dept. of Commerce; issued November 1971,pages 241-243, 290 and 291, incorporated herein by reference. The numberof filaments or fibers employed in the fiber reinforcing element or cordcan vary considerably depending on the ultimate use or servicerequirements. Likewise, the number of strands of fibers used to make afiber reinforcing element or cord can vary widely. In general, thenumber of filaments in the fiber reinforcing element or cord for apassenger car tire can vary from about 500 to 3,000 and the number ofstrands in the reinforcing element can vary from 1 to 10. Preferably thenumber of strands is from 1 to 7 and the total number of filaments about2,000. A representative industry glass tire cord known as G-75 (or G-75,5/0) has 5 strands each with 408 glass filaments. Another representativecord known as G-15 has a single strand containing 2,040 glass filaments.

[0106] The adhesive promoters of the invention can be used in numerousapplications, including bonding the steel braid to the natural and/orsynthetic rubber material of hoses and the metal housing of motormounts.

[0107] The term “vulcanization” used herein means the introduction ofthree dimensional cross-linked structures between rubber molecules.Thus, thiuram vulcanization, peroxide vulcanization, quinoidvulcanization, resin vulcanization, metal salt vulcanization, metaloxide vulcanization, polyamine vulcanization, radiation vulcanization,hexamethylenetetramine vulcanization, urethane cross-linkervulcanization and the like are included in addition to sulfurvulcanization which is usual and most important.

[0108] Rubbers useful in the compositions described herein can benatural rubbers (NR) and/or synthetic rubbers.

[0109] Synthetic rubbers include homopolymers of conjugated dienecompounds, such as isoprene, butadiene, chloroprene and the like, forexample, polyisoprene rubber (IR), polybutadiene rubber (BR),polychloroprene rubber and the like; copolymers of the above describedconjugated diene compounds with vinyl compounds, such as styrene,acrylonitrile, vinyl pyridine, acrylic acid, methacrylic acid, alkylacrylates, alkyl methacrylates and the like, for example,styrene-butadiene copolymeric rubber (SBR),vinylpyridine-butadiene-styrene copolymeric rubber,acrylonitrile-butadiene copolymeric rubber, acrylic acid-butadienecopolymeric rubber, methacrylic acid-butadiene copolymeric rubber,methyl acrylate-butadiene copolymeric rubber, methylmethacrylate-butadiene copolymeric rubber,acrylonitrile-butadiene-styrene terpolymer, and the like; copolymers ofolefins, such as ethylene, propylene, isobutylene and the like withdienes, for example isobutylene-isoprene copolymeric rubber (IIR);copolymers of olefins with non-conjugated dienes (EPDM), for example,ethylene-propylene-cyclopentadiene terpolymer,ethylene-propylene-5-ethylidene-2-norbornene terpolymer andethylene-propylene-1,4-hexadiene terpolymer; polyalkenamer obtained byring opening polymerization of cycloolefins, for example,polypentenamer; rubbers obtained by ring opening polymerization ofoxirane ring, for example, polyepichlorohydrin rubber and polypropyleneoxide rubber which can be vulcanized with sulfur, silicone rubbers, andthe like. Furthermore, halides of the above-described various rubbers,for example, chlorinated isobutylene-isoprene copolymeric rubber(CI-IIR), brominated isobutylene-isoprene copolymeric rubber (Br-IIR),fluorinated polyethylene, and the like are included.

[0110] Particularly, the compositions described herein are characterizedin that the surfaces of the vulcanized rubbers of natural rubber (NR),and synthetic rubbers, e.g. styrene-butadiene copolymeric rubber (SBR),polybutadiene rubber (BR), polyisoprene rubber (IR),isobutylene-isoprene, copolymeric rubber, halides of these rubbers(CI-IIR, Br-IIR) and copolymers (EPDM) of olefins with non-conjugateddienes, which are poor in the adhering ability, are improved to providethem a high adhering ability. Of course, the present invention can beapplied to the other rubbers. All these rubbers may be kneaded withcompounding agents conventionally used for compounding with rubber, forexample, fillers, such as carbon black, silica, calcium carbonate,lignin and the like, softening agents, such as mineral oils, vegetableoils, prior to the vulcanization and then vulcanized.

[0111] The vulcanized rubbers, the surface of which has been treatedwith the adhesion promoter systems described herein can be easilyadhered to the other materials, together with an adhesive resin,particularly metals and polymers, particularly in cord form.

[0112] In order to cure a rubber composition a vulcanizing agent such asa sulfur or peroxide vulcanizing agent is dispersed throughout thecomposition. The vulcanizing agent may be used in an amount ranging from0.5 to 6.0%, based on the weight of the natural and/or synthetic rubbersin the composition, with a range of from 1.0 to 4.0% being preferred.Representative examples of sulfur vulcanizing agents include elementalsulfur (S₈), an amine disulfide, polymeric polysulfide and sulfur olefinadducts. Preferably, the sulfur vulcanizing agent is elemental sulfur.

[0113] Other suitable vulcanizing agents include thiuram, quinoid, metalsalt, metal oxide, polyamine, vulcanization, radiation,hexamethylenetetramine, urethane cross-linker, and the like. Typicalexamples of peroxide vulcanizing agents include dibenzoyl peroxide anddi(tertiary-butyl)peroxide.

[0114] The commonly employed carbon blacks used in conventional rubbercompounding applications can be used as the carbon black in thisinvention. Representative examples of such carbon blacks include N110,N121, N220, N231, N234, N242, N293, N299, S315, N326, N330, M332, N339,N343, N347, N351, N358 and N375.

[0115] The rubber compositions described herein are compounded bymethods generally known in the rubber compounding art, such as mixingthe various sulfur-vulcanizable or peroxide-vulcanizable constituentrubbers with various commonly used additive materials such as, forexample, sulfur donors, curing aids, such as activators and retardersand processing additives, such as oils, resins including tackifyingresins and plasticizers, fillers, pigments, fatty acid, zinc oxide,waxes, antioxidants and antiozonants, retarders and peptizing agents. Asknown to those skilled in the art, the additives mentioned above areselected and commonly used in conventional amounts for tire treadapplications. Typical amount of adhesive resins, comprise about 0.2 toabout 10%, based on the weight of natural and/or synthetic rubbers,usually about 1 to 5%.

[0116] Typical amounts of zinc oxide comprise about 2 to about 5%.Typical amounts of waxes comprise about 1 to about 5% based on theweight of natural and/or synthetic rubbers. Often microcrystalline waxesare used. Typical amounts of retarders range from 0.05 to 2%. Typicalamounts of peptizers comprise about 0.1 to 1%. Typical peptizers may be,for example, pentachlorothiophenol and dibenzamidodiphenyl disulfide.All additive percentages are based on the weight of natural and/orsynthetic rubbers.

[0117] Accelerators may be used to control the time and/or temperaturerequired for vulcanization and to improve the properties of thevulcanizate. The accelerator(s) may be used in total amounts rangingfrom about 0.5 to about 4%, preferably about 0.8 to about 1.5%, based onthe weight of natural and/or synthetic rubbers. Suitable types ofaccelerators that may be used are amines, disulfides, guanidines,thioureas, thiazoles, thiurams, sulfenamides, dithiocarbamates andxanthates. If included in the rubber composition, the primaryaccelerator preferably is a sulfenamide. If a second accelerator isused, the secondary accelerator is preferably a guanidine,dithiocarbamate or thiiram compound.

[0118] When the adhesion promoter systems containing a long chain esterand an adhesive resin are used as a wire coat or bead coat, e.g., foruse in a tire, the adhesion promoter system typically does not includean organo-cobalt compound, and may be used in whole or as a partialreplacement for an organo-cobalt compound which serves as a wireadhesion promoter. When used in part, any of the organo-cobalt compoundsknown in the art to promote the adhesion of rubber to metal also may beincluded. Thus, suitable organo-cobalt compounds which may be employed,in combination with the non-cobalt adhesion promoter systems containinglong chain esters described herein, include cobalt salts of fatty acidssuch as stearic, palrnitic, oleic, linoleic and the like; cobalt saltsof aliphatic or alicyclic carboxylic acids having from 6 to 30 carbonatoms; cobalt chloride, cobalt naphthenate; cobalt carboxylate and anorgano-cobalt-boron complex commercially available under the designationComend A from Shepherd Chemical Company, Cincinnati, Ohio. Comend A isbelieved to have the structure:

[0119] wherein each R, same or different, is an alkyl group having from9 to 12 carbon atoms, and B is a hydrocarbon chain, C₄-C₂₄, straightchain or branched, saturated or unsaturated.

[0120] Amounts of organo-cobalt compound which may be employed dependupon the specific nature of the organo-cobalt compound selected,particularly the amount of cobalt metal present in the compound. Sincethe amount of cobalt metal varies considerably in organo-cobaltcompounds which are suitable for use, it is most appropriate andconvenient to base the amount of the organo-cobalt compound utilized onthe amount of cobalt metal desired in the finished composition.Accordingly, it may in general be stated that if an organo-cobaltcompound is included in the rubber composition, the amount oforgano-cobalt compound present in the stock composition should besufficient to provide from about 0.01 percent to about 0.35 percent byweight of cobalt metal based upon total weight of the rubber in thecomposition, with the preferred amounts being from about 0.03 percent toabout 0.2 percent by weight of cobalt metal based on the total weight ofrubber in the composition.

[0121] The adhesion promoters described herein are especially effectivein compositions in which the rubber is cis-polyisoprene, either naturalor synthetic, and in blends containing at least 25% by weight ofcis-polyisoprene with other rubbers. Preferably the rubber, if a blend,contains at least 40% and more preferably at least 60% by weight ofcis-polyisoprene. Examples of other rubbers which may be blended withcis-polyisoprene include poly-1,3-butadiene, copolymers of 1,3-butadienewith other monomers, for example styrene, acrylonitrile, isobutylene andmethyl methacrylate, ethylene/propylene/diene terpolymers, andhalogen-containing rubbers such as chlorobutyl, bromobutyl andchloroprene rubbers.

[0122] The amount of sulphur in the composition is typically from 2 to 8parts, for example from 3 to 6, by weight per 100 parts by weight ofrubber, but lesser or larger amounts, for example from 1 to 7 or 8 partson the same basis, may be employed. A preferred range is from 2.5 to 6parts per 100 parts by weight of rubber.

[0123] Additional examples of vulcanization accelerators which can beused in the rubber compositions described herein are the thiazole-basedaccelerators, for example 2-mercaptobenzothiazole,bis(2-benzothiazolyl)disulphide, 2(2′,4′-dinitrophenyl-thio)benzothiazole, benzothiazole-2-sulphenamides for instanceN-isopropylbenzothiazole-2-sulphenamide,N-tert-butyl-benzothiazole-2-sulphenamide,N-cyclohexylbenzo-thiazole-2-sulphenamide, and2(morpholinothio)benzothiazole, and thiocarbamylsulphenamides, forexample N,N-dimethyl-N′,N′-dicyclohexylthiocarbamoyl-sulphenamide andN(morpholinothiocarbonylthio)-morpholine. A single accelerator or amixture of accelerators may be used. In the compositions describedherein, these vulcanization accelerators are usually used in amounts offrom 0.3 to 2, for example from 0.3 to 1.5, preferably from 0.4 to 1.0and more preferably from 0.5 to 0.8, parts by weight per 100 parts byweight of rubber.

[0124] The adhesion promoters described herein are very effective inpromoting bonding between rubber and brass, for example the bondingbetween rubber and brass-coated steel. The brass typically has a coppercontent of from 60 to 70% by weight, more especially from 63 to 68% byweight, with the optimum percentage depending on the particularconditions under which the bond is formed. The brass coating onbrass-coated steel can have a thickness of, for example, from 0.05 to 1micrometer, preferably from 0.07 to 0.7 micrometer, for example from0.15 to 0.4 micrometer.

[0125] The long chain ester additive/resin combinations (i.e., adhesionpromoter systems) described herein are particularly useful to adhererubber to steel cord, where conventional adhesive pretreatment has beenlargely ineffective. Rubber can also be bonded effectively to alloys ofcooper and zinc containing small amounts of one or more other metals,for example cobalt, nickel or iron.

[0126] For bonding rubber to zinc, as for example in bonding rubber tozinc-coated steel cords (which are widely used in the manufacture ofconveyor belting) cobalt compounds have been used as adhesion promoters.Examples of such compounds are cobalt naphthenate and the cobalt-boroncomplexes described in GB 2 022 089 A.

[0127] Vulcanization of the rubber composition described herein isgenerally carried out at conventional temperatures ranging from about100° C. to 200° C. Preferably, the vulcanization is conducted attemperatures ranging from about 110° C. to 180° C. Any of the usualvulcanization processes may be used such as heating in a press or mold,heating with superheated steam or hot air or in a salt bath.

[0128] Upon vulcanization of the rubber composition at a temperatureranging from 100° C. to 200° C., the rubber composition can be used forvarious purposes. For example, the vulcanized rubber composition may bein the form of a tire, belt, hose, motor mounts, gaskets and airsprings. In the case of a tire, it can be used for various tirecomponents. Such tires can be built, shaped, molded and cured by variousmethods which are known and will be readily apparent to those havingskill in such art. When the rubber composition is used in a tire, itsuse may be in a wire coat, bead coat, tread, apex, sidewall andcombination thereof. As can be appreciated, the tire may be a passengertire, aircraft tire, truck tire, and the like. Preferably, the tire is apassenger tire. The tire may also be a radial or bias, with a radialtire being preferred.

[0129] The invention may be better understood by reference to thefollowing examples in which parts and percentages are by weight unlessotherwise indicated.

[0130] In Part I of this project, compounds were mixed into existingEPDM recipes and tested for adhesion. The following varieties weretested: Variable Example 1 Example 2 Example 3 Example 4 Example 5Cyrez ® Cyrez ® Control- Cyrez ® Cyrez ® CRA- CRA- Current CRA- CRA-133M 148M EPDM 133M/ 148M/ Formula RX-13804 RX-13804

[0131] The melamine-formaldehyde resins are known as adhesion promotersin the tire industry. The need for rubber-to-cord adhesion generallyrequires the presence of a methylene donor/methylene acceptor resinsystem, as described above. The typical system consists ofhexakismethoxymethylmelamine (HMMM) as the donor and a Novolak resin(such as resorcinol) as the acceptor. Results The table below showsadhesion results with polyester cord in Examples 1-5. Adhesion-lbs-forceCompound Variable Room Temperature 257° C. Example 1: 23.48 2.91(Cyrez ® CRA-133M) Example 2: 21.57 3.58 (Cyrez ® CRA-148M) Example 3:22.21 4.88 (Control) Example 4: 48.76 10.21 (Cyrez ® CRA-133M/ RX-13804)Example 5: 47.70 14.21 (Cyrez ® CRA-148M/ RX-13804)

[0132] The control (Example 3) was EPDM with the polyester cordpretreated with a melamine formaldehyde resin and an adhesive from LordCorporation (Cary, N.C.). The polyester cord used in Examples 1, 2, 4,and 5 were treated with melamine formaldehyde resin but not with anadhesive. Examples 1 and 2 contain just the melamine resin and providebasically equal adhesion to the control compound, which is significantsince the cords used were not coated with adhesive. Examples 4 and 5contain a combination of resin and the esters described herein, and showan unexpected increase in adhesion. The adhesive forces for Examples 4and 5 are increased at least 100% compared to the control and resin onlyExamples (1-3).

[0133] These results indicate that the resin/ester combination providesa dramatic increase in adhesive force between EPDM and polyester cordcompared to the control compound and the compounds containing onlyresin.

[0134] The formulation and data collected for Examples 1-5 are shown inTable I: TABLE I Example 1 Example 2 Example 3 Example 4 Example 5Nordel P3720 (EPDM) 100.00 —————————————————————————→ N762 Carbon Black56.00 —————————————————————————→ Kadox 930 Zinc Oxide 5.00—————————————————————————→ Ricon 150 5.00 —————————————————————————→SR350 4.00 —————————————————————————→ Cyrez ® CRA-133M 7.00 — — 7.00 —Cyrez ® CRA-148M — 7.00 — — 7.00 RX-13804 — — — 10.00 10.00 Subtotal177.00 177.00 170.00 187.00 187.00 MILL ADDITION Vulcup 40KE 7.00—————————————————————————→ Total 184.00 184.00 177.00 194.00 194.00Cyrez ® Cyrez ® Cyrez ® Cyrez ® CRA-133M/ CRA-148M/ CRA-133M CRA-148MControl RX-13804 RX-13804 Major Variable Example 1 Example 2 Example 3Example 4 Example 5 Viscosity and Curing Properties Mooney Viscosity at212° F. Minimum Viscosity 41.3 41.9 41.8 30.3 33.9 t5, minutes 56.8Mooney Viscosity at 250° F. Minimum Viscosity 31 32.7 34.9 25.9 28.5 t5,minutes 10.8 11.1 9.7 8.3 8.3 t10, minutes 11.8 12.8 11.3 9.3 9 t35,minutes 13.8 18.3 17 11.8 Oscillating Disc Rheometer at 350° F. M_(L) 199 8.3 6.3 8.8 M_(H) 151.9 159.3 156.6 57.8 62.9 t_(s)2, minutes 0.920.92 0.83 0.92 1.2 t′c(90), minutes 7.5 7.2 7.9 5.7 6.3 1.25 * t′c(90),minutes 9.4 9 9.9 7.1 7.8 Cure Rate Index 15.2 16 14.1 21.1 19.7 Note:Cpds 4 & 5 Stuck To Rheometer & Press Mold Original Physical PropertiesStress @ 100% Elongation, MPa 13.1 14.1 15.2 4.7 4.9 f~SI 1905 2050 2200680 705 Stress @ 200% Elongation, MPa 99 95 Stress @ 300% Elongation,MPa Tensile Ultimate, MIPa 19.0 18.1 18.7 12.5 10.9 psi 2760 2625 27051815 1580 Elongation @ Break, % 135 120 115 250 235 Hardness Duro A,pts. 83 83 80 78 75 Specific Gravity 1.1043 1.1085 1.1061 1.1075 1.1081

Adhesion Promoter PART II

[0135] Based on Part I results which show improved adhesion of EPDMrubber to polyester cord, the resin/ester combination was evaluated in astandard natural rubber compound used for metal cord adhesion.

[0136] The compounds tested in this study were varied in ester content,with resin content kept constant. The following Table II lists theadhesion results for original, air oven aging, and humidity aging, inExamples 6-12, with parts by weight of resin and ester set forth inparentheses. TABLE II Standard Cyrez ® CRA-148 Resorcinol M(8)/SM(3.85)/melamine Cyrez ® CRA- Cyrez ® CRA- Cyrez ® CRA- Cyrez ® CRA-RX-13804(6)/ formaldehyde Cyrez ® CRA- 148M(8)/SM 148M(8)/SM 148M(8)/SM148M(8)/SM Sulfur(8.4)/Vulkacit (4.23) 148M RX-13804(8) RX-13804(6)RX-13804(4) RX-13840(2) (0.75) Recipe Variable Example 6 Example 7Example 8 Example 9 Example 10 Example 11 Example 12 Adhesion to SteelCord Original Properties: Max. Force, lbs. (avg.) Average 176.2 156162.7 162.6 138.6 167.4 162 Coverage, % 100 95 100 100 100 99 100 AirOven Aging: 48 hrs. @ 121° C. (250° F.) Max. Force, lbs. (avg.) Average105.6 73.5 68.9 70.8 77.6 87.7 123 Coverage, % 99 93 97 97 99 95 95Force Change, % −40 −53 −58 −57 −44 −48 −24 Adhesion to Steel CordHumidity Aging: 7 Days @94° C. (200° F.) Max. Force, lbs. (avg.) Average152.3 119.7 130.4 160.3 137.7 136.9 152.7 Coverage, % 100 98 100 100 100100 99 Force Change, % −14 −23 −20 −1.4 −0.65 −18 −5.7 Humidity Aging:14 Days @94° C. (200° F.) Max. Force, lbs. (avg.) Average 123.7 94.9130.2 115.3 116.8 125.3 148.6 Coverage, % 88 75 93 90 90 90 95 ForceChange, % −30 −39 −20 −29 −16 −25 −8.3 Humidity Aging: 21 Days @94° C.(200° F.) Max. Force, lbs. (avg.) Average 101.4 64.4 82.6 107.9 90.3108.1 127.3 Coverage, % 87 75 70 77 83 83 93 Force Change, % −43 −59 −49−34 −35 −35 −21

[0137] The original wire cord adhesion results show the standardformulation to have slightly higher adhesion than formulationscontaining resin/ester combinations. The formulations containingresin/ester combinations are all very similar except for the resin/estercombination of 8/4. At this time, the reason why this formulation haspoorer original adhesion is not known.

[0138] The humidity aging results are interesting in that Examples 9, 11and 12 have the highest force levels and lowest percent change from theoriginal. Example 12 has a 50% increase in curing agent amount to offsetthe addition of ester to the compound. This formulation had the highestforce recorded and the least change from the original adhesion. Thissuggests that an increase in the amount of curing agent can, along withthe resin/ester combination, improve aged adhesion. All the resin/estercompounds except for Example 8 (resin 8/ester 8) exhibited lower changesin recorded force than the standard compound.

[0139] The formulation for Examples 6-12 are shown in Table III. TABLEIII Example 6 Example 7 Example 8 Example 9 Example 10 Example 11Example 12 SMR-L 100.00 —————————————————————————————————————————→ N32660.00 —————————————————————————————————————————→ Kadox 930 10.00—————————————————————————————————————————→ Cobalt Naphthenate 2.00—————————————————————————————————————————→ Stearic Acid 1.20—————————————————————————————————————————→ Santoflex 13 1.00—————————————————————————————————————————→ PVI 0.20—————————————————————————————————————————→ Pennacolite (3.85)/ 8.08 — —— — — — Resimene (4.23) Cyrez ® CRA-148M — 8.08 8.00 8.00 8.00 8.00 8.00SM RX-13 804 — — 8.00 6.00 4.00 2.00 6.00 Subtotal 182.48 182.48 190.40188.40 186.40 184.40 188.40 Mill Addition Sulfur 5.60——————————————————————————→ 8.40 Vulkacit DZ 0.50—————————————————————————→ 0.75 Total 188.58 188.58 196.50 194.50 192.50190.50 197.55 Cyrez ® CRA-148 M(8)/SM Pennacolite Cyrez ® CRA- Cyrez ®CRA- Cyrez ® CRA- Cyrez ® CRA- RX-13804(6)/ (3.85)/ Cyrez ® 148M(8)/SM148M(8)/SM 148M(8)/SM 148M(8)/SM Sulfur(8.4)/Vulkacit Resimene (4.23)CRA-148M RX-13804(8) RX-13804(6) RX-13804(4) RX-13804(2) (0.75) MajorVariable Example 6 Example 7 Example 8 Example 9 Example 10 Example 11Example 12 Viscosity and Curing Properties Mooney Viscosity @ 168° C.(335° F.) Min. Viscosity 70.2 67.9 57.9 59.7 62.1 63.7 48.1 t5, minutes1.4 1.8 1.9 1.8 2.2 2 1.7 t10, minutes 1.8 2 2.2 2.2 2.5 2.3 2 t35,minutes 2.9 2.6 2.8 2.8 3.3 2.9 2.6 Oscillating Disc Rheometer at 168°C. (335° F.) M_(L) 16.6 16.9 14.1 14.8 15.7 15.8 16 M_(H) 47.5 26.6 23.624.6 22.2 38.8 73.6 t_(s)2, minutes 1.4 1.8 1.8 1.8 1.8 1.8 1.6 t′c(90),minutes 5.3 4.5 4.7 4.7 4.4 4.9 5.3 1.25 * t′c(90), 6.7 5.6 5.8 5.8 5.56.2 6.7 minutes Cure Rate Index 25.6 36.4 35.2 35.2 37.5 31.6 26.7Original Physical Properties Stress @ 100% 7.0 5.9 3.9 5.1 5.0 5.8 7.6Elongation, MPa psi 1010 855 565 740 730 845 1105 Stress @ 200% 14.812.4 8.8 10.9 10.8 12.1 14.8 Elongation, MPa Stress @ 300% — 19.2 14.817.1 16.9 18.6 — Elongation, MPa Tensile Ultimate, 20.4 20.9 21.5 20.621.2 20.7 20.1 MPa psi 2960 3025 3116 2990 3080 3010 2915 Elongation @275 330 415 370 380 335 285 Break, % Hardness Duro 79 78 72 75 76 77 79A, pts. Specific Gravity AVERAGE 1.204 AVERAGE AVERAGE AVERAGE — 1.203

[0140] The use of the resin/ester combination in a sulfur-cured naturalrubber formulation can improve wire cord adhesion after heat aging andhumidity aging as compared to a standard natural rubber formulation.

[0141] In order to verify that the increased cure system of Example 12was not solely responsible for the increased adhesion performance ofExample 12, an additional formulation, Example 13, was tested. The onlydifference between Examples 6 and 13 is that Example 13 has a 50%increase in the amount of cure system additives (Sulfur and Vulkacit).Table IV provides comparative data which demonstrates that increasingthe cure system of the “control compound” (i.e., the prior artformulation of Example 6) by 50% does not lead to an increased adhesiveeffect. Accordingly, these data confirm that the increase in adhesionobserved in Example 12 cannot solely be attributed to the increasedamount of cure system additives, i.e., the increased adhesion is due tothe adhesion promoter. TABLE IV Recipe Variable Pennacolite Cyrez ®Pennacolite(3.85)/ (3.85)/ CRA-148M(8)/ Resimene(4.23)/ Resimene SMRX-13804(6)/ Sulfur(8.4)/ (4.23) Sulfur(8.4)/ Vulkacit(0.75) “Control”Vulkacit(0.75) Example 13 Example 6 Example 12 SMR-L 100 ——————————

N 326 60 ——————————

Kadox 930 10 ——————————

Cobalt 2 ——————————

Napthenate Stearic Acid 1.20 ——————————

Santoflex 13 1.00 ——————————

PVI 0.20 ——————————

Pennacolite 8.08 8.08 — (3.85)/ Resimene(4.23) Cyrez ® CRA- — — 8.00148M SM RX-13804 — — 6.00 Subtotal 182.48 182.48 188.40 Mill AdditionSulfur 8.40 5.60 8.40 Vulkacit 0.75 0.50 0.75 Total 191.63 188.58 197.55Major Variable Cyrez ® Pennacolite(3.85)/ Pennacolite CRA-148M(8)/Resimene(4.23)/ (3.85)/ SM RX-13804(6)/ Sulfur(8.4)/ Resimene(4.23)Sulfur(8.4)/ Processing Vulkacit(0.75) “Control” Vulkacit(0.75)Properties Example 13 Example 6 Example 12 Viscosity and CuringProperties Mooney Viscosity at 168° C. (335° F.) Minimum 69.3 77.2 66.4Viscosity t5, minutes 1.3 1.2 1.3 t10, minutes 1.6 1.3 1.6 t35, minutes2.3 1.9 2.2 Oscillating Disc Rheometer at 168° C. (335° F.) M_(L) 17 2017.3 M_(H) 100.5 101.1 88.4 t_(s)2, minutes 1.4 1.5 1.7 t′c(90), minutes6.7 9.6 5.9 1.25 * t′c(90), 8.3 12 7.4 mins. Cure Rate Index 19.1 12.423.5 Vulcanizate Properties Original Physical Properties Stress @ 100%8.1 6.5 5.9 Elongation, MPa psi 1170 945 850 Stress @ 200% 15.7 13.711.5 Elongation, MPa Stress @ 300% — — 16.9 Elongation, MPa TensileUltimate, 18.4 20.1 18.7 MPa psi 2665 2920 2710 Elongation @ 240 300 330Break, % Hardness Duro 82 80 80 A, pts. Specific Gravity 1.201 1.1991.204 Adhesion to Steel Cord Original Properties: Maximum Force, lbs.(avg). Set 1 90.1 104.4 80.3 Set 2 78.4 99.3 80.6 Set 3 82.4 101.1 103.3Average 83.6 101.6 88.1 Coverage, % 90 90 90

Adhesion Promoter Part III

[0142] Next, natural rubber-to-metal bonding was evaluated to determinethe effect of added ester(s), as described herein. This presents a largepotential for automotive parts, such as motor mounts, brakes, hoses, andthe like.

[0143] The first study focused on long chain esters in natural rubberand their effect on adhesion to metal (see Table V - Examples 14-17).The data indicate that the adhesion promoters described herein improveadhesion to brass in a sulfur-cured rubber formulation. The use of theresin/ester combination did not improve adhesion versus compounds withester only. TABLE V Example Example Example Example 14 15 16 17 SMR-L100.00 ——————————

Kadox 930 5.00 ——————————

Stearic Acid 2.00 ——————————

N 330 35.00 ——————————

Cyrez ® CRA-148M 6.95 — 6.95 — RX-13804 6.95 5.00 6.95 — Subtotal 155.90147.00 155.90 142.00 Mill Addition Sulfur 2.25 — — — Santocure TBSI 0.70— — — DiCup 40KE — 5.00 ————————

Total 158.85 152.00 160.90 147.00 Major Variable RX-13804/ RX-13804/Cyrez ® Cyrez ® Control CRA-148M RX-13804 CRA-148M Example Example 14Example 15 Example 16 17 Viscosity and Curing Properties MooneyViscosity at 335° F. (168° C.) Minimum 47.5 46.5 62 56 Viscosity t5,minutes 2 1.1 0.75 0.85 t10, minutes 2.3 1.3 0.85 1 t35, minutes 3 1.71.1 1.8 Oscillating Disc Rheometer at 335° F. (168° C.) M_(L) 13.4 12.411.4 13.1 M_(H) 41.9 67 74.2 74.6 t_(s)2, minutes 1.8 1.3 1.2 1.1t′c(90), minutes 7.2 13.6 15.3 14.5 1.25 * t′c(90), 9 17 19.1 18.1minutes Cure Rate Index 18.7 8.1 7.1 7.5 Original Physical PropertiesStress @ 100% 2.0 4.0 5.5 5.1 Elongation, MPa psi 290 575 800 735 Stress@ 200% 5.6 14.7 — — Elongation, MPa Stress @ 300% 10.6 — — — Elongation,MPa Tensile 16.5 16.4 9.9 16.2 Ultimate, MPa psi 2390 2385 1440 2355Elongation @ 440 215 140 190 Break, % Hardness Duro 52 57 62 61 A, pts.Specific Gravity 1.097 1.082 1.105 1.090 Metal Sulfur Peroxide PeroxidePeroxide Adhesion- ASTM D429 Brass Adhesion Force, 82.58 1.69 — — lbf/inwidth Failure Type R R R R % Failure 100 100 100 100 Aluminum AdhesionForce, — — — — lbf/in width Failure Type R R R R % Failure 100 100 100100 Steel Adhesion Force, — — — — lbf/in width Failure Type R R R R %Failure 100 100 100 100

[0144] Table VI provides data wherein a sulfur cure system was used informulations containing resin only (Example 18), a resin combined with along chain ester of the disclosure (Example 20), and a controlcontaining no resin and no ester (Example 19). From these data, it canbe seen that the adhesion promoter system including a long chain esterand an adhesive resin performs best, and gives superior adhesive resultswhen compared with the control formulation and the formulationcontaining the resin, but not including an ester of the disclosure.TABLE VI Recipe Variable Cyrez ® CRA Cyrez ® CRA Resin Resin 148M“Control” 148M/RX-13804 Example 18 Example 19 Example 20 SMR-L 100—————————————

Kadox 930 5.00 —————————————

Stearic Acid 2.00 —————————————

N 330 35.00 —————————————

Cyrez ® Resin 7.00 — 7.00 148-M RX-13804 — — 7.00 Subtotal 149.00 142.00156.00 Mill Addition Sulfur 2.25 2.25 2.25 Santocure TBSI 0.70 0.70 0.70Total 151.95 144.95 158.95 Viscosity and Curing Properties MooneyViscosity at 168° C. (335° F.) Minimum 48.1 53.2 48.2 Viscosity t5,minutes 2.1 1.5 2 t10, minutes 2.4 1.8 2.3 t35, minutes 3.2 2.6 2.9Oscillating Disc Rheometer at 168° C. (335° F.) M_(L) 13.7 14.6 13.5M_(H) 31.2 36 40.9 t_(s)2, minutes 1.8 1.7 1.8 t′c(90), minutes 5.3 5.37.1 1.25 * t′c(90), 6.7 6.7 9 mins. 28.6 27.3 19 Cure Rate IndexVulcanizate Properties Original Physical Properties Stress @ 100% 1.91.8 2.0 Elongation, MPa psi 280 255 300 Stress @ 200% 4.7 4.5 5.6Elongation, MPa Stress @ 300% 8.6 8.8 10.6 Elongation, MPa TensileUltimate, 22.1 24.5 16.5 MPa psi 3205 3560 2380 Elongation @ 555 565 440Break, % Hardness Duro 57 55 52 A, pts. Specific Gravity — — 1.097 MetalAdhesion - ASTM D249 Brass Adhesion Force, 118.2 46.3 138.9 lbf/in widthFailure Type R, RM R R, RM % Failure Type 95, 5 100 95, 5 AluminumAdhesion Force, Fail Fail Fail lbf/in width Failure Type RM RM RM %Failure 100 100 100 Steel Adhesion Force, Fail Fail Fail lbf/in widthFailure Type RM RM RM % Failure 100 100 100

[0145] Next, the effect of the long chain esters described herein wasevaluated in an EPDM rubber formulation for rubber to metal bonding. Thecure system was also evaluated to determine the effect of peroxideversus a sulfur system. The sulfur formulations did not work, thus theseformulations were discarded. The peroxide cured formulations were variedby using the ester alone and the resin/ester combination. The data belowin Table VII (Examples 21-23), lists adhesion results for brass,aluminum and steel cord in EPDM. TABLE VII RX-13804/Cyrez ® RX-13804CRA-148M Control Major Variable Example 21 Example 22 Example 23 BrassAdhesion Force, 1.26 52.43 — lbf/in. width Failure Type R R R % Failure100 100 100 Aluminum Adhesion Force, — — — lbf/in. width Failure Type RR R % Failure 100 100 100 Steel Adhesion Force, 16.82 19.97 — lbf/in.width Failure Type R R R % Failure 100 100 100

[0146] The formulation containing the resin/ester has significantlygreater adhesion to brass than the formulation with just ester, and thecontrol. The steel adhesion results show that the formulation with esterdoes provide some adhesion, but the resin/ester combination isunexpectedly better. The control formulation has no adhesion to steel.None of the formulations has adhesion to aluminum.

[0147] The recipe/formulation data for Examples 21-23 is shown in TableVIII: TABLE VIII Example 21 Example 22 Example 23 Nordel IP 3720 100————————

N 762 56 ————————

Kadox 930 5.00 ————————

Ricon 150 5.00 ————————

SR 350 4.00 ————————

RX-13804 10.00 7.00 — Cyrez ® Resin — 10.00 — 148M Subtotal 180.00187.00 170.00 Mill Addition VulCup 40KE 7.00 ————————

Total 187.00 194.00 177.00 Major Variable RX-13804/ Cyrez ® RX-13804CRA-148M Control Example 21 Example 22 Example 23 Peroxide CureViscosity and Curing Properties Mooney Viscosity at 168° C. (335° F.)Minimum 23.9 29.6 33.6 Viscosity t5, minutes 9.5 11.2 7.5 t10, minutes10.7 11.9 7.9 t35, minutes — 15.8 8.8 Oscillating Disc Rheometer at 168°C. (335° F.) M_(L) 6.6 12.2 9.2 M_(H) 87.1 92.4 177 t_(s)2, minutes 0.920.92 0.83 t′c(90), minutes 6.5 8.4 8.5 1.25 * t′c(90), 8.1 10.5 10.6minutes Cure Rate Index 17.9 13.3 13 Original Physical Properties Stress@ 100% 1.4 6.5 13.7 Elongation, MPa psi 198 940 1990 Stress @ 200% 11.212 — Elongation, MPa Stress @ 300% — — — Elongation, MPa TensileUltimate, 12.2 13.0 19.7 MPa psi 1770 1890 2860 Elongation @ 200 210 135Break, % Hardness Duro A, 80 83 86 pts. Specific Gravity 1.0998871.122098 1.114178

[0148] Table IX provides comparative data that supplements the datapresented in Table VIII. Example 24, contains resin, but does notcontain any of the long chain esters disclosed herein. As can be seenfrom the data of Table IX, Example 24 did not promote adhesion betweenEPDM and metal substrates.

[0149] Table IX also contains formulations wherein the ester was varied.A saturated ester, UBS 020602, in accordance with the disclosure, wasused to formulate Examples 25 and 26. In Example 25, the saturated esteradditive was not combined with an adhesive resin as described herein,and failed to promote adhesion between EPDM and the metal substrates.However, in Example 26, the saturated ester was combined with anadhesive resin, and excellent adhesion between metal substrates andEPDM, more particularly between steel and EPDM, was obtained. TABLE IXRX-13804/Cyrez ® UBS 020692/ CRA-148M Cyrez ® CRA-148M UBS 020602Cyrez ® CRA-148M Control Recipe Variable Example 22 Example 24 Example25 Example 26 Example 23 Nordel IP 3720 100.00———————————————————————————→ N762 56.00 ———————————————————————————→Kadox 930 5.00 ———————————————————————————→ Ricon 150 5.00———————————————————————————→ SR 350 4.00 ———————————————————————————→ RX13804 7.00 — — — — Cyrez ® Resin 148M 10.00 10.00 — 10.00 — UBS 020602 —— 7.00 7.00 — Subtotal 187.00 180.00 177.00 187.00 170.00 Mill AdditionVulcup 40 KE 7.00 ———————————————————————————→ Total 194.00 187.00184.00 194.00 177.00 UBS 020602 Recipe Variable RX-13804/148M Cyrez ®CRA-148M UBS 020602 Cyrez ® CRA-148M Control Processing PropertiesExample 22 Example 24 Example 25 Example 26 Example 23 Viscosity andCuring Properties Mooney Viscosity at 121° C. (250° F.) MinimumViscosity 26.3 32.6 23.4 26.6 28.7 t5,minutes 12.8 9.8 11.4 11.1 9.7t10, minutes 14.2 10.4 12.3 11.8 10.2 t35, minutes FAIL 12.7 17.8 14.811.4 Oscillating Disc Rheometer at 177° C. (350° F.) M_(L) 6.7 10.8 6.78 8.8 M_(H) 74.1 115.9 129 87.4 171.6 t_(s)2, minutes 0.92 0.92 1.1 1 1t′c(90), minutes 7.4 10.1 9.1 9.3 10.3 1.25 * c(90),minutes 9.3 12.611.4 11.6 12.9 Cure Rate Index 15.4 10.9 12.5 12.1 10.7 VulcanizateProperties Original Physical Properties Stress @ 100% 6.1 9.3 8.4 6.313.4 Elongation, MIPa psi 890 1350 1220 920 1945 Stress @ 200% 11.7 — —— — Elongation, MPa Stress @ 300% — — — — — Elongation, MPa TensileUltimate, MPa 12.3 15.2 14.1 12.0 18.2 psi 1785 2200 2045 1735 2635Elongation @ Break, % 205 160 145 180 125 Hardness Duro A, pts. 85 87 8583 87 Specific Gravity 1.119 1.128 1.102 1.120 1.110 Metal Adhesion -ASTM D429 Brass Adhesion Force, 91 61.5 FAIL 77.6 FALL lbf/in. widthFailure Type R R RM R RM %Failure 100 100 100 100 100 Aluminum AdhesionForce, FAIL FAIL FAIL FAIL FAIL Ibf/in. width Failure Type RM RM RM RMRM % Failure 100 100 100 100 100 Steel Adhesion Force, FAIL 35.3 FAIL 77FAIL lbf/in. width Failure Type R RM RM RM-R RM % Failure 100 100 10067%, 33% 100

EPDM Rubber to Metal Bonding

[0150] Additional esters were evaluated to determine their effect onadhesion when combined with an adhesive resin. The esters evaluated wereas follows: Plasthall A saturated diester based on 2-ethyihexyl alcoholand DOS sebacic acid. RX-13577 An unsaturated monoester based ontridecyl alcohol and tall oil fatty acid. RX-13824 An unsaturateddimerate ester based on tridecyl alcohol and a C-36 dimer acid. Thisester is similar to RX-13804, which uses the same dimer acid, butRX-13804 is reacted with 2- hylhexyl alcohol (di-2-ethylhexyl dimerate).

[0151] The results indicate that the compound with DOS/resin providesgood adhesion to brass and steel. The RX-13577/resin compound hasexcellent adhesion to brass and steel, and the force values for steelare greater than any of the other ester/resin combinations. The datasuggests that a greater degree of ester unsaturation levels providesgreater adhesion because RX-13577 does have more unsaturated sites byweight than RX-13804 or RX-13824. Another piece of data that helpssupport the above statement is the steel adhesion data for the esteronly compounds. The RX-13577 compound had the only measurable adhesionwhile DOS and RX-13824 had no adhesion values.

[0152] The data is set forth in Table X, Examples 27-34: TABLE X Example27 Example 28 Example 29 Example 30 Example 31 Example 32 Example 33Example 34 Nordel IP 3720 100.00 —————————————————————————————————→ N76256.00 —————————————————————————————————→ Kadox 930 5.00—————————————————————————————————→ Ricon 150 5.00—————————————————————————————————→ SR 350 4.00—————————————————————————————————→ Plasthall DOS 10.00 7.0 — — — — — —Cyrez ® CRA- — 10.00 7.00 — 10.00 — 10.00 — 148M RX-13577 — — — 10.007.00 — — — RX-13824 — — — — — 10.00 7.00 — Control — — — — — — — —Subtotal 180.00 187.00 177.00 180.00 187.00 180.00 187.00 170.00 MillAddition Vulcup 40KE 7.00 —————————————————————————————————→ TOTAL187.00 194.00 184.00 187.00 194.00 187.00 194.00 177.00 PlasthallRX-13577 RX-13824 Plasthall DOS DOS/Cyrez ® Cyrez ® CRA- Cyrez ® CRA-Cyrez ® CRA- Control (dioctylsebacate) CRA-148M 148M RX-13577 148MRX-13824 148M Example Major Variable Example 27 Example 28 Example 29Example 30 Example 31 Example 32 Example 33 34 Plasticizer ProcessingProperties Viscosity and Curing Properties Mooney Viscosity at 250° F.(121° C.) Mi Viscosity 19.9 26.1 32.2 21.1 26.1 21.3 26.8 30.9 t5,minutes 8.6 9.6 8.4 7.6 7.3 8.9 7.8 6.6 t10, minutes 9.3 11.8 8.9 8.67.9 9.8 8.3 6.9 t35, minutes FAIL FAIL 17.6 FAIL FAIL FAIL 10.2 8.3Oscillating Disc Rheometer at 350° F. (177° C.) M_(L) 5.5 6.6 10 6.6 7.26.4 8.6 9.7 M_(H) 88.6 63.1 84.9 58.8 52.8 75.3 58.5 125.8 t_(s)2,minutes 0.92 0.92 0.92 1.3 0.92 1 0.92 0.83 t′c(90),mins 6.3 6 6.1 6.9 66.1 5.9 6.3 1.25 * t′c(90), 7.8 7.5 7.6 8.7 7.5 7.6 7.4 7.8 mins. CureRate Index 18.8 19.7 19.4 17.6 19.7 19.7 20 18.5 Original Phys.Properties Stress @ 100% 4.8 5.0 6.4 3.8 4.5 4.2 4.7 8.2 Elongation, MPapsi 700 725 925 545 655 615 680 1195 Stress @ 200% 11.4 9.4 12.3 7.5 7.89.7 8.2 — Elongation, MPa Stress @ 300% — — — 11.1 10.4 — — —Elongation, MPa Tensile 13.5 11.1 13.9 12.7 10.4 11.7 10.4 18.1Ultimate, MPa psi 1960 1650 2010 1835 1515 1690 1515 2620 Elongation @220 250 225 320 300 235 275 175 Break, % Hardness Duro 81 84 86 79 82 8082 85 A,pts. Specific Gravity 1.102 1.123 1.125 1.098 1.118 1.098 1.1211.113 Metal Adhesion - ASTM D429 Brass Adhesion force, — 128.1 51.1 —139.4 — 133.5 — lbf/in. width Failure Type RM RM R RM R RM R RM %Failure 100 100 100 100 100 100 100 100 Aluminum Adhesion force, — — — —— — — — lbf/in. width Failure Type RM RM RM RM RM RM RM RM % Failure 100100 100 100 100 100 100 100 Steel Adhesion force, — 37.3 — 14.2 96.7 —42.3 — lbf/in. width Failure Type RM RM RM RM RM RM RM RM % Failure 100100 100 100 50 100 100 100

Chlorinated Polyethylene Rubber to Polyester Cord

[0153] More specifically, RX-13845 was evaluated for cord or fabric torubber adhesion. RX-13845 is an adhesion promoter system consisting of36 wt. % RX-13804, 36 wt. % Cyrez CRA-138 Resin (a liquid at roomtemperature), and 28% substrate (synthetic calcium silicate). RX-13845was prepared by adding preheated Cyrez CRA 138 resin liquid to a drycarrier (substrate) contained in a mixing bowl, followed by addition ofpreheated RX-13804. The materials were mixed at low speed for 3 minutes.The materials were blended for an additional 3 minutes. RX-13845 permitsliquids to be handled as powders. Because the active adhesion promoteris released, the active ingredient is released from the carrier,incorporation of RX-13845 into a rubber compound allows the adhesionpromoter to function in the same manner as if it had been incorporatedinto rubber as a neat material.

[0154] The results demonstrate a significant improvement in adhesion ofuntreated nylon fibers, isocyanate treated nylons, isocyanate treatedaramid fibers, and untreated polyester fibers to chlorinatedpolyethylene polymer. The data is set forth in Table XI, Examples 34-38.TABLE XI Example Example Example Example 35 36 37 38 Tyrin CPE CM 0730100.00 —————————————

N 774 Carbon Black 55.00 —————————————

N 650 Carbon Black 30.00 —————————————

Albacar 5970(CaCO₃) 10.00 —————————————

PARAPLEX ® G-62 15.00 —————————————

PLASTHALL ® TOTM 30.00 —————————————

Calcium Oxide 4.40 —————————————

Flectol TMQ 0.20 —————————————

RX-13845 — 3.00 6.00 10.00 Subtotal 244.60 247.60 250.60 254.60 MillAddition Vulcup 40KE 9.50 —————————————

Triganox 17/40 3.50 —————————————

PLB 5405(75%) 6.70 —————————————

Total 264.30 267.30 270.30 274.30 Major Variable RX-13845 RX-13845RX-13845 Control (3) (6) (10) Viscosity and Curing Properties MooneyViscosity at 132° C. (270° F.) Minimum Viscosity 40.7 40.4 38.2 37.0 t5,minutes 2.2 2.2 2.3 2.3 t10, minutes 2.5 2.5 2.5 2.5 t35, minutes 3.03.0 3.2 3.0 Oscillating Disc Rheometer at 160° C. (320° F.) M_(L) 9.411.9 10 9.4 M_(H) 48.7 42.2 38.4 37 t_(s)2, minutes 1.3 1.2 1.7 1.5t′c(90), minutes 25.8 28.3 29.7 21.8 1.25 * t′c(90), minutes 32.3 35.437.1 27.3 Cure Rate Index 4.1 3.7 3.6 4.9 Original Physical PropertiesStress @ 100% 6.4 6.2 6.3 5.4 Elongation, MPa psi 930 905 920 790 Stress@ 200% 11.7 10.9 11.1 9.2 Elongation, MPa Stress @ 300% — — — —Elongation, MPa Tensile Ultimate, MPa 13.5 12.5 12.8 10.5 psi 1965 18201850 1530 Elongation @ Break, % 250 255 250 275 Hardness Duro A, pts. 8080 80 78 Specific Gravity 1.323 1.326 1.324 1.324 UNTREATED NYLONAverage Adhesion Force, 8.43 7.97 9.63 10.13 lbf/in width std.dev 1.311.60 1.23 1.19 ISOCYANATE TREATED NYLON Average Adhesion Force, 24.8427.90 30.24 34.93 lbf/in width std.dev 1.51 4.56 4.54 3.95 RubberFailure ———————————

UNTREATED ARAMID Average Adhesion Force, 5.54 4.09 6.44 4.80 lbf/inwidth std.dev 0.57 1.12 0.76 0.46 ISOCYANATE TREATED ARAMID AverageAdhesion Force, 5.50 8.20 9.78 9.32 lbf/in width std.dev 0.31 1.03 2.270.88 UNTREATED POLYESTER Average Adhesion Force, 8.90 9.72 17.77 17.39lbf/in width std.dev 1.33 0.33 4.59 6.49

Method of Measuring Cord Adhesion

[0155] Esters were evaluated to determine their effect on adhesion ofcords to rubbers when combined with an adhesive resin. The followingmethod is for determining the relative strip-peel adhesion ofreinforcing fibers, including natural and manmade filaments and spunyarns, to various rubber compounds and elastomers. This method isconventionally used with industrial weight fibers of 500 denier orgreater. Typically, the most common elastomers and compounds employedare natural rubber, styrene butadiene rubber, copolymers of olefins withnon-conjugated dienes (EPDM), polychloroprene rubber (CR), acrylonitrilebutadiene elastomer (NBR), chlorosuphonated polyethylene elastomer(CSM), polyisoprene rubber, isobutylene-isoprene copolymeric rubber,chlorinated isobutylene-isoprene copolymeric rubber, brominatedisobutylene-isoprene copolymeric rubber, polyvinylchloride, urethane,and blends thereof, but this technique can be modified to determinefiber adhesion to a wide variety of materials.

[0156] The adhesion testing described herein was performed in accordancewith ASTM D 4393-85 “Strap Peel Adhesion of Reinforcing Cords or Fabricsto Rubber Compounds.”

[0157] Typically, 1″×5″ strips of fiber/rubber composite materials wereprepared for testing. Fibers were positioned onto a tape backing using arotatable cylinder. The tape backing was applied to a milled elastomeror rubber compound under high temperature and pressure in a hydraulicpress (i.e., at curing, extruding, or other conditions) to form a cord-or fabric-reinforced composite material. The composite was then cut intostrips for adhesion measurements (e.g., through separation load values,appearance, etc.).

[0158] Procedure

[0159] An ASTM 429 mold was placed in a compression press (capable ofachieving temperatures between 250° F. and about 400° F., and a pressureof about 125 tons) and the temperature was set within ±2° F. of thevulcanization temperature (cure temperature) for the specific rubbercompound used. The press was maintained within the specified temperaturerange for about 30 minutes.

[0160] Three strips of 3″ wide masking tape (a suitable masking tape is#515 Masking Tape, Anchor Continental, Inc. Columbia, S.C.), withadhesive side out, were wrapped around the rotatable cylinder. The threestrips were overlapped to achieve a tape backing having a total width ofabout 7″. Six 1″ wide fiber samples were wrapped onto the tape backing.The same or different yarn samples can be wound onto each tape backing.Each fiber or cord sample should be wound, however, such that there isno overlapping of fibers and no space between adjacent fibers.Typically, three strips of each fiber sample were prepared and tested.

[0161] The fibers were secured with 1″ wide masking tape, and the stripswere marked A, B, C, D, E, and F. The six wound samples were removedfrom the cylinder by cutting across the cylinder.

[0162] A 5″×7″ piece of unvulcanized compounded rubber to be tested,which has been milled to a specified thickness (0.250±0.20 inches), wascut. The mold surface which will be in contact with the fiber assemblywas cleaned with n-heptane.

[0163] The preheated mold was removed from the press. The fiber sampleswere placed at the bottom mold plate with the masking tape backing facedown, and the fibers facing up. A 1″×7″ strip of aluminum foil wasplaced on the back edge of the fiber samples so that the fibers areperpendicular to the aluminum foil and about one inch of their lengthcovers the aluminum foil strip. Each strip has a specified position inthe press. The cleaned 5″×7″ unvulcanized rubber slab was then on top onthe fiber assembly. The preheated top mold plate was placed on top ofthe samples to form a sandwich of mold top plate, rubber compound,aluminum foil, yarn samples, tape and bottom plate. This sandwich isthen placed in the preheated compression press and a pressure of about125 tons is applied. The pressure and temperature are maintained for thespecified time (cure time).

[0164] The mold assembly was removed from the press at the end of thecure time. It is important not to disturb the fiber composite whileseparating the pad from the mold plates. Typically, the pad was placedin cold water to expedite the cooling process. The pad was cooled toambient temperature prior to marking the pad for identification.

[0165] The adhesion pad should sit for an extended period (“conditioningperiod”), e.g., overnight, prior to cutting into the 1″×5″ strips foradhesion testing. As much of the aluminum foil strip as possible wasremoved to give a starting separation between the fiber sample and therubber compound. The foil can be left in place if too difficult toremove. After conditioning, each 5″×7″ rubber section was cut into six1″×5″ strips such that only one fiber to be tested is contained in eachstrip.

[0166] Each 1″×5″ adhesion composite strip was tested on the Instron4201 tensile/compression machine (Instron Corporation, Canton, Mass.)according to method 08 of the Instron Series IX Materials Testing™Software. TABLE XII Material Chemical Description Supplier SMR-L Naturalrubber Alcan Kadox 930 Zinc Oxide The C. P. Hall Company Stearic AcidR.G. Stearic Acid, rubber grade The C. P. Hall Company N-330 CarbonBlack JM Huber or Degussa Spider Sulfur Elemental Sulfur The C. P. HallCompany Santocure TBSI N-tert-butyl-di(2- Harwick Standardbenzothiazolesulfen)imide RX-13577 Tridecyl tallate The C. P. HallCompany RX-13804 Di(2-ethylhexyl)dimerate The C. P. Hall CompanyRX-13824 Ditridecyl Dimerate The C. P. Hall Company Plasthall DOSDioctyl sebacate The C. P. Hall Company Paraplex A-8000 PolyesterAdipate The C. P. Hall Company Staflex DBM Dibutyl maleate The C. P.Hall Company DiCup 40 KE Dicumyl Peroxide on Burgess Clay HerculesRX-13845 36% RX-13804, 36% Cyrez ® D- The C. P. Hall Company 148M, 28%Hydrated Amorphous Silica Cyrez ® Resin Melamine Resin Powder CytecD-148M Concentrate N-326 Carbon Black JM Huber Cobalt Naphthenate MetalCarboxylate adhesion Sheperd promoter Santoflex 13N-Isopropyl-N′-phenyl-p- Harwick phenylenediamine PVI N-(cyclohexylthio)phthalimide Flexsys Pennacolite Resin Formaldehyde Resin IndspecVulkacit DZ Benzothiazl-2-dicyclohexyl- Bayer sulfenamide ResimeneHexamethoxymelamine Solutia Nordel IP3720 Hydrocarbon Rubber DuPont N762Carbon Black JM Huber Ricon 150 Liquid Polybutadiene Ricon TMTDTetramethyl thiuram disulfide R. T. Vanderbilt Rotax2-mercaptobenzothiazole R. T. Vanderbilt SR 350 Acrylic Ester SartomerUBS020602 Di(2-ethylhexyl) dimerate, The C. P. Hall Company hydrogenatedCyrez ® Resin CRA- Melamine Resin Powder Cytec 133M concentrate Cyrez ®Resin CRA- Melamine Resin Powder Cytec 148M concentrate Royalene 501Ethylene-propylene ethylidene Uniroyal norbomene rubber 57/43 EP RatioRoyalene 502 ENB third monomer 62/38 EP ratio Uniroyal N-550 CarbonBlack Engineering Carbon RX-13782 Capric Tallate The C. P. Hall CompanyRX-13805 Di(2-ethylhexyl) dimerate The C. P. Hall Company RX-13806Didecyl dimerate The C. P. Hall Company RX-13853 Di-hexyldecyl tallateThe C. P. Hall Company UBS 020602 Di (2-ethyihexyl) dimerate (Pripol TheC. P. Hall Company 1006) UBS 120601 polyester dimerate The C. P. HallCompany UBS 121201 polyester dimerate The C. P. Hall Company Sunpar 2280Paraffinic Oil Sun Oil Premix MBT 2-mercaptobenzothiazole The C. P. HallCompany Premix TMTD Tetramethyl thiuram disulfide The C. P. Hall CompanyPremix DPTT Dipentamethylene thiurum The C. P. Hall Company(tetra)sulfide Premix TDEC Tellurium diethyldithiocarbamate The C. P.Hall Company UBS051602 Dioleyl dimerate The C. P. Hall Company UBS060302Ditridecyl dimerate The C. P. Hall Company BM050702 Pentaerythritoltetratallate The C. P. Hall Company Royalene IM7200 blend ofethylene-propylene- Uniroyal ethylidene norbomene rubber withpolyethylene dust 76/24 EP Ratio RX-13822 Tridecyl dimerate The C. P.Hall Company RX-13823 Polyester dimerate The C. P. Hall Company Trigonox145-45B-pd 2,5-dimethyl-2,5-di-(tert- Akzo Nobel butylperoxy)hexyne-3,45% supported on calcium carbonate Tyrin CPE CM 0730 chlorinatedpolyethylene 30% Dupont Dow chlorine N-774 carbon black DegussaEngineered Carbons N-650 carbon black Degussa Engineered Carbons Albacar5970 calcium carbonate The C. P. Hall Company Paraplex G-62 epoxidizedsoybean oil The C. P. Hall Company RX-13845 Micro Cel E 28 wt. %,RX-13804 The C. P. Hall Company 36 wt. %, Cyrez ® CRA-138M 36 wt. %Micro Cel E Calcium Silicate The C. P. Hall Company Cyrez ® CRA-138MMelamine Formaldehyde resin Cytec Cyrez ® CRA-148M Melamine Formaldehyderesin Cytec VulCup 40KE 2,2′-bis(tert-butylperoxy Harwick Standarddiisopropylbenzene Triganox 17/40 4,4-bis(tert-butyl peroxy)-3,3,5- AkzoNobel trimethylcyclohexane PLB 5405 (75%) Trimethylolpropane trimethylFlow Polymer Incorporated acrylate SMR CV 60 Natural Rubber Process OilC-255E Parraffinic Oil The C. P. Hall Company RX-13896 Di(2-ethylhexyl)dimerate The C. P. Hall Company (Unidyme 22) Sulfur Sulfur The C. P.Hall Company Santocure TBBS N-t-butyl-2- Harwick Standardbenzothiazolesulfenamide Hallco TE-577 Tridecyl Tallate The C. P. HallCompany RX-13653 pentaerythritol tetratallate The C. P. Hall CompanyRX-13892 Diolelyl dimerate The C. P. Hall Company Calcium Oxide CalciumOxide The C. P. Hall Company Plasthall TOTM 72 wt. % TrioctylTrimellitate, 28 The C. P. Hall Company wt. % Hydrated Amorphous SilicaFlectol TMQ 2,2,4-Trimethyl-1,2- Flexsys dihydroquinoline, polymerizedUntreated nylon fiber Beaver Manufacturing Co. Powerloc Isocyanatetreated nylon fiber Beaver Manufacturing Co. Untreated aramid fiberBeaver Manufacturing Co. Beaverloc Isocyanate treated aramid fiberBeaver Manufacturing Co. Untreated polyester fiber Beaver ManufacturingCo.

[0167] In accordance with an important feature of the compositions,methods and articles described herein, the combination of one or more ofthe long chain esters described herein and combined with the melamine-or phenol- containing adhesive resin (the combination being referred toherein as the “adhesion promoter” or “adhesion promoter system”) can beused in liquid form by providing the ester/resin adhesion promoter insolution (1) by solubilizing both components with one or more suitableorganic solvents or (2) by emulsifying the ester and resin components inwater with one or more suitable emulsifying agents. The water-basedemulsion should have an HLB value of about 4 to about 5 for best esterdispersion in the emulsion. In liquid form, the adhesion promoter has anumber of advantages, particularly the ability to coat a substrate, suchas a metal or polymeric substrate, with the liquid ester/resin adhesionpromoter for adherence of an elastomer to the substrate, withoutchanging the composition of the elastomer. Other advantages include (1)the ability to prepare a concentrated, master batch of the adhesionpromoter having a relatively high concentration, e.g., 50-90% by weightof the adhesion promoter that can be diluted upon addition to anelastomeric composition or upon substrate coating; (2) the ability toinclude excess alcohol, e.g., 2-ethylhexanol, during the synthesis ofthe long chain ester portion of the liquid adhesion promoter, for use asa solvent for solubilizing the resin portion of the liquid adhesionpromoter. The use of excess alcohol during the synthesis of the estersis particularly advantageous for ester synthesis since theesterification reaction proceeds faster with excess alcohol. Since theexcess alcohol is useful in solubilizing the resin, the excess alcoholcan remain with the synthesized ester without removing much, or any, ofthe excess alcohol in an ester concentration or purification step.

[0168] The liquid adhesion promoter, whether solubilized in an organicliquid or emulsified in a water-based emulsion, can be added to theelastomeric composition for adhesion to a substrate, e.g., a metal,polymeric layer, film, or fibrous, e.g., fabric, substrate, or can beused to pre-treat, e.g., coat, the substrate, e.g., a metal or apolymeric layer, film, fibrous or fabric substrate for adhesion of theelastomer thereto. In another embodiment, the substrate, for example,polymeric sheets, films, fibers, yarns and/or fabrics, e.g., nylon,glass, ARAMID, or polyester, can be pretreated with the resin componentof the adhesion promoter system (known in the art as an “isocyanatepretreatment”) for adhesion of the substrate to an elastomer. Theresin-treated substrate then can be treated with the ester component ofthe adhesion promoter system for improved adherence of the elastomer tothe substrate. The resin-treated substrate can be ester treated in anymanner, preferably by dipping or coating the resin-treated substratewith an organic solution of the ester or a water-based emulsioncontaining the ester. Alternatively, the ester can be added to theelastomer for contact with and adherence to the resin-treated substrate,or the ester and resin combination (adhesion promoter system) can beapplied to the substrate as a coating, which preferably is dried priorto contact with the elastomer. As previously disclosed, the adhesionpromoter system can be added directly to the elastomer composition.

[0169] The organic solution (RX-13928, hereinafter “Solution”) andwater-based emulsion (RX-13937 hereinafter “Emulsion”) versions of theliquid adhesion promoters described herein were tested for adherence tovarious elastomers. The organic solution version of the adhesionpromoter was tested (1) by adding the organic solution directly to theelastomer compositions, and (2) by pre-treating the substrate with thecombined ester/resin adhesion promoter composition. The water-basedemulsion was tested only by pre-treating the substrate prior toelastomer adherence. The data are shown in the following Tables XIII toXV. In the following Tables XIII to XV, substrates pre-treated with theliquid adhesion promoter compositions (whether organic solution orwater-based emulsion) were oven dried for 30 hours at 65° C. prior toapplying the elastomer. TABLE XIII Solvent Based Liquid AdhesionPromoter For Brass Control Solution Solution RX-13804 RX-13892 Recipe 12 3 4 5 Elastomer Composition (Parts by wt.) Nordel IP 3720 (EPDM)100.00 N 762 56.00 Kadox 930 5.00 Ricon 150 5.00 SR 350 4.00 Solution —8.00 10.00 — RX-13804 — — — 4.00 — RX-13892 — — — — 4.00 Subtotal 170.00178.00 180.00 174.00 174.00 Mill Addition (Parts by wt.) VULCUP 40KE7.00 Total 177.00 185.00 187.00 181.00 181.00 Major Variable ProcessingProperties Mooney Viscosity at 120° C. (250° F.) Minimum Viscosity 28.422.8 21.1 25.0 24.6 t5, minutes 8.9 8.9 9.3 9.4 9.9 t10, minutes 9.4 9.510.0 10.0 10.6 t35, minutes 11.0 >60 >60 12.3 >60 Oscillating DiscRheometer at 177° C. (350° F.) M_(L) 8.0 6.4 6.5 7.8 7.9 M_(H) 110.586.0 82.1 99.9 105.4 t_(s)2, minutes 0.9 1.0 1.0 1.0 1.0 t′c(90),minutes 6.4 6.8 7.2 7.3 8.4 1.25 * t′c(90), minutes 8.0 8.5 9.0 9.2 10.5Cure Rate Index 18.2 17.2 16.2 15.8 13.5 Recipe JEKS1-170 Major VariableOriginal Physical Properties Stress @ 100% Elongation, MPa 11.2 6.2 5.88.0 8.3 psi 1625 905 840 1155 1205 Tensile Ultimate, MPa 16.7 14.2 12.215.7 15.2 psi 2415 2060 1770 2280 2205 Elongation @ Break, % 135 195 195170 165 Hardness Duro A, pts. 85 82 82 83 84 Specific Gravity 1.10581.104 1.103 1.104 1.101 Metal Adhesion-ASTM D429 Solution Treated Brass(painted brass- like primer) Adhesion Force, lbf/in. width 60.03 74.1216.23 77.4 71.43 Failure Type R R RM R R % Failure 100 55 100 100 100Emulsion Treated Brass Adhesion Force, lbf/in. width Fail Fail 20.6439.02 54.94 Failure Type RM RM RM RM R % Failure 100 100 100 100 100

[0170] TABLE XIV Water-Based Emulsion Liquid Adhesion Promoter For BrassControl Emulsion Emulsion Recipe JEKS1-150 1 2 3 Nordel IP 3720 100.00100.00 100.00 N 762 56.00 56.00 56.00 Kadox 930 5.00 5.00 5.00 Ricon 1505.00 5.00 5.00 SR 350 4.00 4.00 4.00 Emulsion 8.00 10.00 Subtotal 170.00178.00 180.00 Mill Addition VULCUP 40KE 7.00 7.00 7.00 TOTAL 177.00185.00 187.00 Major Variable Control Emulsion Emulsion 8.00 10.00Viscosity and Curing Properties Mooney Viscosity at 121° C. (250° F.)Minimum Viscosity 28.00 26.4 26.4 t5, minutes 10.5 13.4 9.8 t10, minutes11.0 14.5 10.3 t35, minutes 12.7 18.9 >60.0 Oscillating Disc Rheometerat 177° C. (350° F.) M_(L) 12.3 11.5 11.6 M_(H) 120.5 86.3 73.7 t_(s)2,minutes 0.9 0.9 1.0 t′c(90), minutes 7.0 8.5 7.5 1.25 * t′c(90), minutes8.8 10.6 9.4 Cure Rate Index 16.5 13.2 15.4 Original Physical PropertiesStress @ 100% Elongation, MPa 10.9 6.5 5.6 psi 1575 945 810 Stress @200% Elongation, MPa — 13.3 10.4 Stress @ 300% Elongation, MPa — — —Tensile Ultimate, MPa 16.8 13.3 10.9 psi 2440 1935 1585 Elongation @Break, % 135 200 210 Hardness Duro A, pts. 84 84 84 Specific Gravity1.113 1.110 1.111 Metal Adhesion-ASTM D429 Adhesion Force, lbf/in. widthFail 22.8 23.3 Failure Type RM RM RM % Failure 100 100 100

[0171] TABLE XV Liquid Adhesion Promoter System For ARAMID Fiber RecipeJEKS1-100 1 Elastomer Composition (chlorinated polyethylene) Tyrin CP0730 100.00 N 774 Carbon Black 55.00 N 650 Carbon Black 30.00 Albacar5970(CaCO₃) 10.00 PARAPLEX G-62 15.00 PLASTHALL TOTM 30.00 Calcium Oxide4.40 Flectol TMQ 0.20 Subtotal 244.60 Mill addition Vulcup 40KE 9.50Triganox 17/40 3.50 PLB 5405(75%) 6.70 TOTAL 264.30 Major VariableControl Viscosity and Curing Properties Mooney Viscosity at 132° C.(270°F.) Minimum Viscosity 40.2 t5, minutes 2.5 t10, minutes 3.0 t35, minutes4.8 Oscillating Disc Rheometer at 160° C.(320° F.) M_(L) 9.7 M_(H) 40.6t_(s)2, minutes (Continued) 1.3 t′c(90), minutes 15.8 1.25 * t′c(90),minutes 19.8 Cure Rate Index 6.9 Original Physical Properties Stress @100% Elongation, MPa 5.2 psi 760 Stress @ 200% Elongation, MPa 9.5Stress @ 300% Elongation, MPa — Tensile Ultimate, MPa 11.5 psi 1665Elongation @ Break, % 260 Hardness Duro A, pts. 78 Specific Gravity1.329 Yarn Adhesion-CPH Method EMULSION TREATED ARAMID 1008 AverageAdhesion Force, lbf/in. width 7.67 std. dev 1.16 SOLUTION TREATED ARAMID1008 Average Adhesion Force, lbf/in. width 8.34 std. dev 1.51 UNTREATEDTWARON ARAMID 1008 Average Adhesion Force, lbf/in. width 5.23 std. dev0.83 BEAVERLOC 102 TWARON ARAMID Average Adhesion Force, lbf/in. width10.64 std. dev 0.75 Weight Retention After 30 hrs. @ 65° C. SOLUTIONWeight Retention, grams 1.45 Weight Retention, % 48.70 EMULSION WeightRetention, grams 1.48 Weight Retention, % 49.70

[0172] The following Table XVI is a summary of the solvent solubilitiesof the melamine (Resimene 3520) and RX-13804 (di-2-ethylhexyl dimerate)for use in selecting solvents capable of solubilizing both the ester andthe resin in making a liquid solution of the adhesion promoter. Thesolubilities were only determined at 1:1 mixtures of solvent todimerate/melamine. If both the samples were soluble in the solvent, thesolutions were again mixed at a 1:1 ratio of dimerate+solvent toMelamine+solvent. The samples provide complete solubility of bothdimerate ester and Melamine resin so long at the composition is at a 13%by weight or greater percent solvent level. TABLE XVI Melamine/DimerateSolubilities Spot Checks RX13804 + Solvent RX13804 Melamine MelamineXylene S S S 1,4-Dioxane S S S Toluene S S S Acetonitrile I S I EthanolI S I n-Hexanol S S S Ethyl Acetate S S S N,N-Dimethylformamide I S In-Butanol S S S 2-EH (2-ethylhexanol) S S S Methyl Ethyl Ketone S S SMethyl Isobutyl Ketone S S S Butyl Acetate S S S Chloroform S S S CarbonTetrachloride S S S Hexane S I I Heptane S I I Isopropanol S S SIsodecyl alcohol S S S Isotridecyl alcohol S S S Ethylene glycolmonobutyl ether S S S Dipropylene glycol monobutyl S S S etherMelamine/Dimerate Solubilities with 2-EH Quantitative Sample % RX13804 %Melamine % 2-EH Appearance 1 42.5 42.5 15.0 Clear 2 43.0 43.0 14.0 Clear3 43.2 43.2 13.6 Clear 4 43.3 43.3 13.4 Clear 5 43.5 43.5 13.0 Hazy(Insoluble)

[0173] In order to homogeneously emulsify the ester and/or the resincomponents of the adhesion promoter in a water-based carrier, anysuitable emulsifying/dispersing agents can be used that are capable offorming a stable emulsion. Since the esters have a very low polarity andthe resins have a very high polarity, if both the ester and resin areemulsified in a water-based carrier, generally a combination ofemulsifying agents is needed to provide a homogeneous, stable emulsionin water. It has been found that the water-based emulsions should have ahydrophile/lipophile balance (HLB) in the range of about 4 to about 5for best emulsification. Particular combinations of emulsifying agentsfound to be especially effective in providing a homogeneous, stablewater-based emulsion of the dimerate esters and adhesive resin include acombination of an anionic metal stearate, e.g., potassium stearate forthe ester, and a non-ionic sorbitan oleate for the adhesive resin, asshown in the following emulsion preparation guide: RX-13804 49 Stearicacid  0.2 {close oversize brace} K Stearate KOH (45%)  0.1 CyrezCRA-138M 48.7 Span80 (sorbitan oleate) (2 to 6%) based on the weight ofdimerate ester (RX-13804)

[0174] After adding Stearic acid, heat up to 90° C.; add KOH slowlywhile mixing, mix for 5 minutes, then cool the mixture down to around50° C. Then add Cyrez, then Span80. Water-Based Emulsion AdhesionPromoter RX-13937 Composition Component % by wt. Chemical SupplierRX-13804 49.0 Di-2-ethylhexyl dimerate CP Hall Stearic acid 0.2 tripledpressed Stearic acid Witco KOH (45%) 0.1 Potassium hydroxide 45% AshtaCyrez CRA-138M 48.7 methylated melamine, Cytec formaldehyde polymerSpan80 2.0 sorbitan monooleate Uniqema

[0175] Solution-Based Adhesion Promoter RX-13928 Composition Component %by wt. Chemical Supplier ester 42.5 Di-2-ethylhexyl dimerate CP Hallresin 42.5 methylated melamine UCB formaldehyde resin solvent 15.02-ethylhexanol Sunoco

What is claimed is:
 1. A rubber composition comprising rubber selectedfrom the group consisting of natural rubber, synthetic rubber, and acombination thereof; and a liquid adhesion promoter selected from thegroup consisting of a solution and a water-based emulsion containing (1)an adhesive resin in an amount of about 0.1% to about 15% by weight,based on the weight of rubber in the composition; and (2) an esterhaving formula I, II, III, IV or a combination of any two or more ofsaid esters in an amount of about 0.1% to about 15% by weight, based onthe weight of rubber in the composition:

wherein R¹ is a C₃-C₂₄ alkyl radical, straight chain or branched,saturated, or unsaturated containing 1 to 3 carbon-to-carbon doublebonds; R² is a C₃-C₂₄ saturated fatty acid residue, or an unsaturatedfatty acid residue having 1 to 6 carbon-to-carbon double bonds;

wherein n=3-24, and R³ and R⁴, same or different, are a C₃-C₂₄ alkylradical, straight chain or branched, saturated, or unsaturatedcontaining 1 to 3 carbon-to-carbon double bonds;

wherein R⁵ and R⁷, same or different, are a C₃-C₂₄ hydrocarbon chain,straight chain or branched, either saturated or having 1 to 6carbon-to-carbon double bonds; R⁶ and R⁸, same or different, are C₃-C₂₄alkyl radical, straight chain or branched, saturated, or unsaturatedcontaining 1 to 3 carbon-to-carbon double bonds; and R¹⁰ and R¹¹, sameor different, are a C₃-C₂₄, saturated hydrocarbon chain, straight chainor branched; or an unsaturated C₃-C₂₄, hydrocarbon chain, straight chainor branched, having 1 to 6, carbon-to-carbon double bonds;

wherein R¹², R¹⁴ and R¹⁸, same or different, are a C₃-C₂₄, hydrocarbonchain, straight chain or branched, either saturated or having 1 to 6carbon-to-carbon double bonds; R¹³, R¹⁵ and R¹⁹, same or different, area C₃-C₂₄ alkyl radical, straight chain or branched, saturated, orunsaturated containing 1 to 3 carbon-to-carbon double bonds; and R¹⁶,R¹⁷ and R²⁰, same or different, are a C₃-C₂₄ saturated hydrocarbonchain, straight chain or branched; or unsaturated C₃-C₂₄ hydrocarbonchain, straight chain or branched, containing 1 to 6 carbon-to-carbondouble bonds.
 2. A rubber composition in accordance with claim 1,wherein the ester is selected from the group consisting of formula I,II, III, IV, and a combination of any two or more of said esters:

wherein R¹ is a C₃-C₁₈ alkyl radical, straight chain or branched,saturated, or unsaturated containing 1 to 3 carbon-to-carbon doublebonds; and R2 is a C₈-C₁₈ saturated fatty acid residue, or anunsaturated fatty acid residue having 1 to 3 carbon-to-carbon doublebonds;

wherein n=6-18, and R³ and R⁴, same or different, are a C₃-C₁₈ alkylradical, straight chain or branched, saturated, or unsaturatedcontaining 1 to 3 carbon-to-carbon double bonds;

wherein R⁵ and R⁷, are a C₆-C₂₄ hydrocarbon chain, straight chain orbranched; either saturated or having 1 to 3 carbon-to-carbon doublebonds; R⁶ and R⁸, same or different, are a C₃-C₁₈ alkyl radical,straight chain or branched, saturated, or unsaturated containing 1 to 3carbon-to-carbon double bonds; and R¹⁰ and R¹¹, same or different, are aC₃-C₁₈, saturated hydrocarbon chain, straight chain or branched; or anunsaturated hydrocarbon chain, straight chain or branched, containing 1to 3 carbon-to-carbon double bonds;

wherein R¹², R¹⁴ and R¹⁸, same or different, are a C₈-C₁₈, hydrocarbonchain, straight chain or branched, either saturated or having 1 to 3carbon-to-carbon double bonds; R¹³, R¹⁵ and R¹⁹, same or different, area C₆-C₁₈ alkyl radical, straight chain or branched, saturated, orunsaturated containing 1 to 3 carbon-to-carbon double bonds; and R¹⁶,R¹⁷ and R²⁰, same or different, are a C₆-C₁₈ saturated hydrocarbonchain, straight chain or branched; or an unsaturated C₆-C₁₈hydrocarbon-chain, straight chain or branched, containing 1 to 3carbon-to-carbon double bonds.
 3. The rubber composition of claim 1,wherein the adhesive resin is a condensation product of a methyleneacceptor and a methylene donor.
 4. The rubber composition in accordancewith claim 3, wherein the adhesive resin is selected from the groupconsisting of phenol-formaldehyde, melamine-formaldehyde;naphthol-formaldehyde; polyepoxide; a reaction product of triallylcyanurate, resorcinol, and formaldehyde; a reaction product ofp-chlorophenol, resorcinol, and formaldehyde; a copolymer of styrene,butadiene, and 2-vinylpyridine; and mixtures thereof.
 5. The rubbercomposition in accordance with claim 4, wherein the phenol-formaldehyderesin is resorcinol-formaldehyde.
 6. The rubber composition inaccordance with claim 1, wherein the adhesive resin is selected from thegroup consisting of derivatives of melamine, acetoguanamine,benzoguanamine, cyclohexylguanamine and glycoluril monomers andoligomers of these monomers, which have been substituted on average attwo or more positions on the monomer or on each unit of the oligomerwith vinyl terminated radicals, the rubber composition being free ofresorcinol.
 7. The rubber composition in accordance with claim 6,wherein at least one of the adhesive resins has been further substitutedon average at one or more positions with a radical which comprisescarbamoylmethyl or amidomethyl.
 8. A rubber composition in accordancewith claim 6, wherein the adhesive resin is selected from compounds ofthe formula:

and positional isomers thereof, wherein, in each monomer and in eachpolymerized unit of the oligomers, Y is selected from methyl, phenyl andcyclohexyl, and, on average, at least two R are —CH₂-R¹, and anyremaining R are H, and at least 2 R¹ are radicals selected fromCH₂══C(R²)—C(O)—O—, CH₂══C(R²)—C(O)-Z, CH₂══C(R²)—C(O)—NH—, andCH₂══C(R²)—CH₂—O—, wherein R² is hydrogen or C₁-C₁₈ alkyl, and Z is aradical selected from —O—CH₂—CH₂—O—, —O—CH₂—CH(CH₃)—O—,—O—CH₂—CH₂—CH₂O—, and —O—CH(C₂H₅)—O—, and any remaining R¹ radicals areselected from —O-R³, —NH—C(O)—OR⁴, and —NH—C(O)-R⁴, and wherein R₃ ishydrogen or R₄, and R₄ is a C₁-C₁₈ alkyl, alicyclic, hydroxyalkyl,alkoxyalkyl or aromatic radical, and in the oligomers, P is 2 to about10, and L is methylene or the radical —CH₂—O—CH₂—.
 9. A rubbercomposition in accordance with claim 8, wherein on average at least oneR¹ in each monomer or in each oligomerized unit of the adhesive resinis: —NH—C(O)—OR⁴ wherein R⁴ is as defined in claim
 8. 10. A rubbercomposition in accordance with claim 9, wherein the adhesive resin is acompound of the formula

wherein P is 2 to about 10, L is methylene or the radical —CH₂—O—CH₂—,and R is as follows: at least two R are —CH₂-R¹, and any remaining R areH, and at least 2 R¹ are radicals selected from CH₂══C(R²)—C(O)—O—,CH₂══C(R²)—C(O)-Z, CH₂══C(R²)—C(O)—NH—, and CH₂══C(R²)—CH₂—O—, whereinR² is hydrogen or C₁-C₁₈ alkyl, and Z is a radical selected from—O—CH₂—CH₂—O—, —O—CH₂—CH(CH₃)—O—, —O—CH₂—CH₂—CH₂O—, —O—CH(C₂H₅)—O—, andany remaining R¹ radicals are selected from —O-R³, —NH—C(O)—OR⁴, and—NH—C(O)—OR⁴, and wherein R₃ is hydrogen or R₄, and R₄ is a C₁-C₁₈alkyl, alicyclic, hydroxyalkyl, alkoxyalkyl or aromatic radical.
 11. Arubber composition in accordance with claim 10, wherein in the adhesiveresin formulas, on average at least one R radical in each monomer or ineach oligomerized unit is —CH₂—NH—C(O)—OR⁴ wherein R⁴ is a C₁-C₁₈ alkyl,alicyclic, hydroxyalkyl, alkoxyalkyl or aromatic radical.
 12. A rubbercomposition in accordance with claim 10, wherein on average at least twoR radicals are selected fromCH₂══C(CH₃)—C(O)O—C₃H₆—O—CH₂—andCH₂══CH₂—C(O)O—C₂H₄—O—CH₂—and at leastone R radical is selected from CH₂—NH—C(O)—O—CH₃ andCH₂—NH—C(O)—O—C₃H₇.13. A rubber composition in accordance with claim 8, further comprisingan additional additive selected from hydroxymethylated andalkoxymethylated (alkoxy having 1-5 carbon atoms) derivatives ofmelamine, acetoguanamine, benzoguanamine, cyclohexylguanamine andglycoluril and their oligomers.
 14. The composition in accordance withclaim 6, wherein the adhesive resin is a derivative of melamine or anoligomer of melamine.
 15. The composition in accordance with claim 6,wherein the adhesive resin is a derivative of acetoguanamine or anoligomer of acetoguanamine.
 16. The composition in accordance with claim6, wherein the adhesive resin is a derivative of benzoguanamine or anoligomer of benzoguanamine.
 17. The composition in accordance with claim6, wherein the adhesive resin is a derivative of cyclohexylguanamine oran oligomer of cyclohexylguanamine.
 18. A rubber composition inaccordance with claim 1, wherein the adhesive resin is a self-condensingalkylated triazine resin selected from the group consisting of (i),(ii), and (iii): (i) a self-condensing alkylated triazine resin havingat least one of imino or methylol functionality and represented byformula (I)

(ii) an oligomer of (i), or (iii) a mixture of (i) and (ii), wherein Zis —N(R)(CH₂OR¹), aryl having 6 to 10 carbon atoms, alkyl having 1 to 20carbon atoms or an acetyl group, each R is independently hydrogen or—CH₂OR¹, and each R¹ is independently hydrogen or an alkyl group having1 to 12 carbon atoms, provided that at least one R is hydrogen or —CH₂OHand at least one R¹ is selected from the alkyl group; and wherein therubber composition is substantially free of methylene acceptorcoreactants.
 19. The rubber composition in accordance with claim 18,wherein at least one R group of the alkylated triazone resin ishydrogen.
 20. The rubber composition in accordance with claim 19,wherein at least one R¹ group of the alkylated triazone resin is a loweralkyl group having 1 to 6 carbon atoms.
 21. The rubber composition inaccordance with claim 20, wherein the adhesive resin is a derivative ofmelamine, benzoguanamine, cyclohexylguanamine, or acetoguanamine, or anoligomer thereof.
 22. The rubber composition in accordance with claim20, wherein Z is —N(R)(CH₂OR¹).
 23. The rubber composition in accordancewith claim 4, wherein the phenol-formaldehyde resin isresorcinol-formaldehyde; and the melamine-formaldehyde resin isN-(substituted oxymethyl) melamine-formaldehyde.
 24. A rubbercomposition in accordance with claim 1, wherein the ester has theformula II and comprises a saturated diester formed by the reaction ofsebacic acid and a C₆-C₂₄ alcohol, straight chain or branched,saturated, or unsaturated containing 1 to 3 carbon-to-carbon doublebonds.
 25. A rubber composition in accordance with claim 24, wherein thealcohol is 2-ethylhexyl alcohol, and the ester has the followingformula:


26. A rubber composition in accordance with claim 1, wherein the esteris an unsaturated diester formed by the reaction of a C₃₆ dimer acid anda C₃-C₁₈ alcohol, straight chain or branched, saturated, or unsaturatedcontaining 1 to 3 carbon-to-carbon double bonds.
 27. A rubbercomposition in accordance with claim 26, wherein the alcohol is2-ethylhexyl alcohol.
 28. A rubber composition in accordance with claim26, wherein the alcohol is tridecyl alcohol.
 29. A rubber composition inaccordance with claim 26, wherein the alcohol is oleyl alcohol.
 30. Arubber composition in accordance with claim 1, wherein the estercomprises the following dimer acid reacted with a C₃-C₂₄ alcohol:


31. A rubber composition in accordance with claim 1, wherein the estercomprises the following dimer acid reacted with a C₃-C₂₄ alcohol:


32. A rubber composition in accordance with claim 1, wherein the estercomprises the following dimer acid reacted with a C₃-C₂₄ alcohol:


33. A rubber composition in accordance with claim 1, wherein the esteris the reaction product of a C₃-C₂₄ alcohol with a tricarboxylic acid,having the following formula:


34. A rubber composition in accordance with claim 1, wherein the esteris a combination of compounds of formula I, II, III, and IV.
 35. Arubber composition in accordance with claim 34, wherein the ester is areaction product of a C₃-C₂₄ alcohol straight chain or branched,saturated, or unsaturated having 1 to 3 carbon-to-carbon double bonds,with a dimer acid having CAS #61788-89-4.
 36. A rubber composition inaccordance with claim 35, wherein the alcohol is 2-ethylhexyl alcohol.37. A rubber composition in accordance with claim 35, wherein thealcohol is a tridecyl alcohol.
 38. A rubber composition in accordancewith claim 35, wherein the alcohol is an oleyl alcohol.
 39. The rubbercomposition in accordance with claim 1, wherein the R², R⁵, R⁷, R¹², R¹⁴are fatty acid residues derived from animal or vegetable fatty acids.40. The rubber composition of claim 39, wherein the fatty acids areselected from the group consisting of butter; lard; tallow; grease;herring; menhaden; pilchard; sardine; babassu; castor; coconut; corn;cottonseed; jojoba; linseed; oiticia; olive; palm; palm kernel; peanut;rapeseed; safflower; soya; sunflower; tall; tung; and mixtures thereof.41. The rubber composition of claim 40, wherein the fatty acid residuesare selected from the group consisting of hexanoic; octanoic; decanoic;dodecanoic; 9-dodecenoic; tetradecanoic; 9-tetradecenoic; hexadecanoic;9-hexadecenoic; octadecanoic; 9-octadecenoic; 9-octadecenoic,12-hydroxy; 9, 12-octadecadienoic; 9, 12, 15-octadecatrienoic; 9, 11,13-octadecatrienoic; 9, 11, 13-octadecatrienoic, 4-oxo;octadecatetrenoic; eicosanoic; 11-eicosenoic; eicosadienoic;eicosatrienoic; 5, 8, 11, 14-eicosatetraenoic; eicosapentaenoic;docosanoic; 13-docosenoic; docosatetraenoic; 4, 8, 12, 15,19-docosapentaenoic; docosahexaenoic; tetracosenoic; and 4, 8, 12, 15,18, 21-tetracosahexaenoic.
 42. A method of increasing the adhesion of arubber composition to a substrate, said rubber composition including anatural or synthetic rubber, and an adhesive resin, comprising adding tosaid rubber composition, in an amount of about 0.1% to 15% by weight,based on the weight of the rubber, a liquid ester additive of formula I,II, III, IV, or mixtures thereof:

wherein R¹ is a C₃-C₂₄ alkyl radical, straight chain or branched,saturated, or unsaturated containing 1 to 3 carbon-to-carbon doublebonds; R² is a C₃-C₂₄ saturated fatty acid residue, or an unsaturatedfatty acid residue having 1 to 6 carbon-to-carbon double bonds;

wherein n=3-24 and R³ and R⁴, same or different, are a C₃-C₂₄ alkylradical, straight chain or branched;

wherein R⁵ and R⁷, same or different, are a C₃-C₂₄ hydro carbon chain,straight chain or branched, either saturated or having 1 to 6carbon-to-carbon double bonds; R⁶ and R⁷, same or different, are aC₃-C₂₄ alkyl radical, straight chain or branched; and R¹⁰ and R¹¹, sameor different, are a C₃-C₂₄, saturated hydrocarbon chain, straight chainor branched; or an unsaturated C₃-C₂₄, hydrocarbon chain, straight chainor branched, having 1 to 6 carbon-to-carbon double bonds;

wherein R¹², R¹⁴ and R¹⁸, same or different, are a C₃-C₂₄ hydrocarbonchain, straight chain or branched, either saturated or having 1 to 6carbon-to-carbon double bonds; R¹³, R¹⁵ and R¹⁹, same or different, areC₃-C₂₄ alkyl radical, straight chain or branched, saturated, orunsaturated containing 1 to 3 carbon-to-carbon double bonds; and R¹⁶,R¹⁷ and R²⁰, same or different, are C₃-C₂₄ saturated hydrocarbon chain,straight chain or branched; or unsaturated C₃-C₂₄ hydrocarbon chain,straight chain or branched, containing 1 to 6 carbon-to-carbon doublebonds.
 43. A method in accordance with claim 42, wherein the substrateis a plurality of cords.
 44. A method in accordance with claim 42,wherein the substrate is a polymeric sheet or fabric.
 45. A method inaccordance with claim 42, wherein the substrate is flat metal stockmaterial.
 46. A method of increasing the adhesion of a rubbercomposition to a substrate comprising an expedient selected from thegroup consisting of (1) applying a liquid adhesion promoter comprisingan adhesive resin component and an ester component to the substrateprior to contacting the substrate with the rubber composition; (2)contacting the substrate separately with a solvent solution orwater-based emulsion containing the ester component of the liquidadhesion promoter, and contacting the substrate separately with asolvent solution or water-based emulsion containing the adhesive resincomponent of the liquid adhesion promoter prior to contacting thesubstrate with the rubber composition; (3) applying the adhesive resincomponent of the liquid adhesion promoter to the substrate prior tocontacting the adhesive resin-applied substrate with the rubbercomposition containing a solvent solution or water-based emulsioncontaining the ester component of the liquid adhesion promoter; (4)applying the ester component of the liquid adhesion promoter to thesubstrate prior to contacting the ester-applied substrate with therubber composition containing a solvent solution or water-based emulsioncontaining the adhesive resin component of the liquid adhesion promoter;wherein the ester component of the adhesion promoter is selected fromthe group consisting of formulas I, II, III, IV, and a combination ofany two or more:

wherein R¹ is a C₃-C₂₄ alkyl radical, straight chain or branched,saturated, or unsaturated containing 1 to 3 carbon-to-carbon doublebonds; R² is a C₃-C₂₄ saturated fatty acid residue, or an unsaturatedfatty acid residue having 1 to 6 carbon-to-carbon double bonds;

wherein n=3-24, and R³ and R⁴, same or different, are a C₃-C₂₄ alkylradical, straight chain or branched, saturated, or unsaturatedcontaining 1 to 3 carbon-to-carbon double bonds;

wherein R⁵ and R⁷, same or different, are a C₃-C₂₄ hydrocarbon chain,straight chain or branched, either saturated or having 1 to 6carbon-to-carbon double bonds; R⁶ and R⁸, same or different, are C₃-C₂₄alkyl radical, straight chain or branched, saturated, or unsaturatedcontaining 1 to 3 carbon-to-carbon double bonds; and R¹⁰ and R¹¹, sameor different, are a C₃-C₂₄, saturated hydrocarbon chain, straight chainor branched; or an unsaturated C₃-C₂₄, hydrocarbon chain, straight chainor branched, having 1 to 6, carbon-to-carbon double bonds;

wherein R¹², R¹⁴ and R¹⁸, same or different, are a C₃-C₂₄, hydrocarbonchain, straight chain or branched, either saturated or having 1 to 6carbon-to-carbon double bonds; R¹³, R¹⁵ and R¹⁹, same or different, area C₃-C₂₄ alkyl radical, straight chain or branched, saturated, orunsaturated containing 1 to 3 carbon-to-carbon double bonds; and R¹⁶,R¹⁷ and R²⁰, same or different, are a C₃-C₂₄ saturated hydrocarbonchain, straight chain or branched; or unsaturated C₃-C₂₄ hydrocarbonchain, straight chain or branched, containing 1 to 6 carbon-to-carbondouble bonds.
 47. A method in accordance with claim 47, wherein theamount of the adhesive resin component contained in the rubbercomposition or applied to the substrate is about 0.1% to about 15% byweight, based on the weight of rubber in the composition, and the amountof ester component contained in the rubber composition or applied to thesubstrate is about 0.1% to about 15% by weight, based on the weight ofrubber in the composition.
 48. The method of claim 47, wherein therubber composition contains a vulcanizing agent.
 49. A cord-reinforcedarticle of manufacture comprising a plurality of cords selected frompolymeric cords, metal cords, glass cords, and a combination thereof,adhered to the rubber composition of claim 1.